Get a .45 cal.

Uses less powder..

And is well ovah 2000 fps

Heck ..most of the Black powder bench shooters use a .40 cal

I mainly use round ball in my guns but my .32 is a 1/48 twist. The reason for me trying conicals in the 32 is to gain more weight, .310 round ball= 45gr while a maxi ball I think = 105gr.
Look at your state regs and find out what minimum caliber they allow for hunting. A .45 will take down a lot, plus if casting round ball you’re using less lead per bullet. Depending on what type of muzzle loader you buy you can swap barrels out. You can find some cheap deals out there.

Black powder bench ?....hmmmmm now I'm curious

If you are looking at modern cast bullets ,instead of made for muzzleloader conicals, the issue is engraving the rifling. With a long bearing surface you would be hammering them down the barrel.