cutting patches in quantity fast

Paul Mathews,  in his excellent book "the Paper Jacket", recommends the use of 
9 pound onionskin. The right paper quality and weight is critical to the bullet
being used and its diameter.
A little experimentation helps. It also helps to lubricate the paper patch, for
the rifle bore, the bullet, and the lubed patched bullet as it slips into the case 
a great deal easier. A lube of petroleum jelly mixed with beeswax at the % found to be best works.

I use three different thickness of paper, 9 lb, 16 lb, and 24 lb. All are 100% cotton. The thickness of the paper gives an assortment of choices to get to the desired patched diameter from the naked bullet diameter. For instance today I loaded a box of 9.3x57 mm ammo using our 310gn smooth. The bullets drop at .366" diameter and I want a patched diameter of .368". These are patched with 9lb at about .0018 thickness the thinnest paper I use then run through a .368" sizer which not only sizes but also puts a thin film of lube on the patch. In this way there are a few choices of finished patched diameter using all the same material. For instance The same bullet and patch wet patched will be slightly larger in diameter if not run through the sizer. The same bullet and patch dry patched will be slightly larger in diameter than the wet patch. So in that way you have choice of three finished diameters from the same material with only one sizer diameter. If you have a selection of sizer diameters all the better for even more choices.
Another reason for using different thickness of paper is that in some cases you can use the same bullet in different caliber rifles. For instance I use the very same 310gn smooth bullet used today to load ammo for the 9.3 x 57 mm in my 375/06 rifles. The difference is that I patch with 24 lb. paper. 24 lb. is something like .0048" thickness I dont remember for sure but close to that. Bullets get the same double wrap then run through a .377" sizer that irons the patch on for a smooth tight fit with the thin film of lube.
I should also note the patch should be rolled in a direction dependent on the direction of the rifling of the barrel being used. The idea is to have the outside leading edge of the patch spinning into the wind not away from it. The reason is to insure the instant release of the patch as soon as it exits the muzzle.
These are the ways I have been patching bullets with very good results for many years. I have taken a wide range of game with bullets patched this way including grizzly and black bear, moose, and caribou.
I place great favor in patched bullets for hunting because you can use a very soft malleable alloy that will not shatter and will hold together even at a fairly high velocity that would not be achievable without the patch.
With my fumble fingers though there is a limit to how small a bullet I can patch and for me that seems to be about 30 caliber. I have heard of people patching down to 22 caliber but my nose pickers simply will not tolerate such minuscule maneuvers.

Absolutely yes in most cases but there will be some acceptations like with small bore extremely high velocity cartridges.

In the PP world there are two schools of thought as to what is correct. One is traditional patch to bore diameter and the other is modern patch to groove diameter. Both can work well under the right conditions. Traditional patch to bore diameter was established before smokeless powder so applies for the most part to black powder but not exclusively. I have found that patching to bore diameter can work well with smokeless powder as long as the powder burn rate is kept on the fast side of not slower than 2400 on the burn rate chart or perhaps very slightly slower but not much.
450fuller you mentioned wanting to make your 45-70 a 45-90 and this is a way to do it by patching to bore diameter which allows a longer cartridge length but still chambers easily. Another purpose of patching to bore diameter was to be able to keep shooting longer strings of shots even after fouling has built up something that you just cant do if patching to groove diameter.
The more modern way of patching to groove diameter is better suited to smokeless powders and is not limited to powders on the faster end of the burn rate chart. Patching to groove diameter and using fairly hard bullet alloy is fully capable of full velocity loads for cartridges that normally shoot in the 3000 fps range possibly even a little faster.
The way I apply the patch by running the wrapped bullet into a lube sizer with the desired diameter sizer die installed works good to smoothly and uniformly smooth out the patch and at the same time apply a thin film of bullet lube to the patch.
I was shooting some so patched bullets today in a 40-90 Sharps BN using the modern method of patching to groove diameter. I was shooting a smokeless powder load of 22.5gn of Accurate LT-30 powder and my best group of the day at 100 yards was 1.5" my average was closer to 2.5". It is generally accepted in our time that the bottle neck Sharps cases are not as accurate as the straight wall cases. As evidenced by todays shooting as well as the fact that the first Sharps rifles produced for international competition were chambered for bottle neck cases the 40-90 BN among them.
Something I learned long ago in my fervor to acquire knowledge about shooting as well as casting is that not all of what you hear or read is dependable. Dependability comes from knowledge acquired through personal experience and not by listening to self proclaimed experts parroting what they have heard or read but never personally proven.
As for molds for the 45-90 and something so few people seem to consider is the rifling twist rate of your barrel. It is of course a bullets length not weight that will dictate the required rotational velocity for stability but as a simple example I will offer this, for 45 caliber rifles with 1/20" twist up to 500gn bullets, for rifles with 1/18" twist up to 530gn, and for rifles with 1/16" twist up to 550gn bullets. From that you can get an idea of how important the rifling twist rate is to choosing a mold for your rifle.

I nearly forgot to address alloy hardness for patching to bore diameter.  Of necessity bullets patched to bore diameter must be quite soft not harder than about BHN-10 and softer is better even including pure lead.  Bullets patched to bore diameter are much like muzzleloader bullets in that for accuracy they are dependent on obturation to gain full depth contact with the rifling grooves.  Too hard an alloy causing insufficient obturation and all bets are off for accuracy.  The beauty of PP is that it allows the use of pure lead at fairly high velocity and still have no leading issues what so ever.  For game bullets pure lead is king !