Hi Pat,
the actual twist of a barrel is the LEAST important thing to consider in terms of accuracy alone. I know that fly's in the face of the modern gun-scribes, but as a barrel maker, I have experimented with this, and it's true.

Quality and rifling geometry are FAR more important. I once made some barrels with 3 to one rifling (grooves 3X wider then lands) and ran the twist at 1-18" and shot them for accuracy with round balls. The all shot into one ragged hole at 50 yds. With the fast twist, I needed to wipe the fouling out every shot, but don't let someone convince you that fast can't shoot a ball well. It sure can

with that said, I must tell the rest of the story.
I also made barrels with 1-48, 1-56 and 1-76 twist, all made with 3 to 1 ruifling, and all shot into very small groups at 50 yds.

The ones twisted at 1-48" and longer didn't foul as much and could be re-loaded easily without wiping.

So when buying a barre3l for a round ball gun, look to rifling geometry and over all quality. If the twist is 1-36" or slower, don't worry about it for 28 cal, 32 cal, and 36 cal. If it's 1-40" or slower, don't worry about it for 40 cal, 45 cal 50 cal 54 cal 58 cal and 62 cal, Over 62 cal you will find that 1-56 or slower is best, and over 70 cal go about 1-72 or less.
Faster twist will allow you to shoot smaller powder charged in any give caliber as a rule, but in calibers up to 50 it's really not much of a factor how much you can lessen the recoil.

I have made a number of 54 cal rifles for men that don't hunt, but want super accurate rifles for competition at 25, 50 and 100 yds and want guns that won't kick over long strings of fire. I use barrels for such rifles twisted at 1-40 and they shoot into one ragged hole. You load 80 gains for hunting, but for hunting you will not need to fire more than 2 shots before you can wipe the bore anyway.

If you are not making a rifle that’s to be used 99% of the time for paper punching, you will find that the barrel makers have worked the twist out about as well as it can be. The art of muzzleloading rifle barrel making is not exactly new, and the men that make them for a living are pretty knowledgeable in it.
Green Mountain, Rice, Colorain, Moodie, Rayl, .....all will make you a barrel that will fill you needs well. There are others too.
On an 8 bore, you just need to define the mission statement first. if you will hunt dangerous game with the rifle more than just “plink’ you should get it rifled about 1-96” to 1-104”
If you are going to shoot half charges most of the time, I’d have it made at 1-56 or so”

My 2 cents worth....................
Steve