I have a 58cal custom Hawken that i shoot up to 120grns in but don't like to shoot it more than about 12 shots in one session and a 54cal but with 70to80grns that i can shoot 20 or more shots at one timeon the bench,but when shooting at game no problem at all.
Shifty, you don't say what you will use your future Leman for--hunting or target.
Below is a antique half stock Leman squirrel rifle and a Jack Brooks Leman Indian trade rifle.
The squirrel rifle is about .36 caliber with a 7/8" x 31-7/8" barrel. The Brooks Leman is .54 caliber with a 1" x 32-1/4" barrel. Both are straight octagon.
I don't have any problem shooting the .54 with 90 grains of 2F GOEX all day. Some people may be a little more sensitive to recoil than others, but the deep crecsent butt plate on this rifle doesn't bother me at all.
If recoil is an issue and you are just going to shoot targets, you might consider something like the .36 caliber squirrel rifle.
I think the little half stock squirrel rifle is as cute as it can be. But there are some indications that it was originally a full stock rifle. The nose cap appears to be a muzzle cap. The underrib is actually three pieces riveted to the barrel. The upper rod pipes are brass instead of iron.
A friend has an antique full stock Leman squirrel rifle with a 36" barrel that in all other respects is the same as this half stock. There is a good chance my squirrel rifle originally had a longer barrel, too.
Anyway, caliber is another way around the Leman butt plate challenge.