The standard cavalry load was 30 grains (it started out heavier, but they backed it down because people couldn't handle the recoil.
There are many people that use the "25 grain" pyrodex pellet. Just drop one in and seat a bullet.
If you want to use real black either 2F or 3F would work. That is about at the top of loadings for 3F, and the bottom for 2.
You can use the fake black, but remember that it is not as heavy as real black. Measure it by volume, not with a scale. Use a volume equivalent to 30 grains of black powder (with pyrodex that comes to, I think, about 25 grains).
Unlike smokeless powder, you want it compressed. NO AIRSPACE in the case. Either powder all the way to the base of the bullet, or something to take up the space between the powder and the bullet.
It looks like you have given me everything I need to try some. It looks like the 25 gr. pellet would be a good way to go. I looked and I do have some pyrodex. The first time I used pyrodex I used the same flask funnel that I used with real black and when I shot it,
it recocked the gun for me and what a recoil. I cut the flask funnel off some and it has worked fine since. This was with a old colonial pistol.