Sometimes, counter intuitively, cast bullets will shoot ok in a rough bore. The drill is to shoot ten soft ones with normal lube at low velocity, clean with Ed's Red, dry patch, shoot ten more, repeat cleaning, repeat shooting, etc., until you have about 80 shots down the tube. The idea is to season the bore by filling the rough spots with lead. Under no circumstances take a wire brush to the bore during the break-in process, and not ever again afterward. The trick afterwards is to choose a bullet alloy and velocity that won't lead a normal barrel because from here on out you don't want to impose drastic cleaning measures that will disrupt the "seasoning". Not a guarantee, but it can't hurt to try it. Certainly jacketed bullets are verboten too unless you want to start the process all over again.
As for paper patching to get your cast bullets up to diameter, good luck. The rough bore will likely shred the paper off and wreck accuracy. But, nothing beats a try but a failure. See what happens!
Oversize bullets are available, but I would measure the throat first (chamber cast or pound cast) and try bullets sized to fit that. Anything larger, in an appropriately sized case neck may well not chamber. If say the throat is .310 (typical) I would try some dead soft .310 bullets at low velocity (1100-1200fps) and see what happens. A fast burning pistol powder might spank the base of the bullet hard enough to bump it up a few thousandths to seal the bore, something you won't get with a medium or slow burning powder.
Do keep us posted. I for one am interested anyways!
