There is a difference between volume and weight for BP shooting.
It's always been 35gr by volume.So, a BP powder measure will work.
If you trying for 35gr by weight,then it's gonna be next to impossible to seat the bullet.
40gr even by volume,seating the bullet will require a lot of pressure.I've did a few.Plus,the bullet will deform.
Plus, a difference between the old "balloon head" and the "solid head" cases.
Back in the late 1800s,the "balloon head" cases were used.Had somewhat more powder space then now.
First of all,yes, please do a lot of reading.
There are many articles on blackpowder cartridges.
I do agree with Sir Charles.
My best to you.