Two reasons I would be very leery of doing that in a "built in the Black Powder era" rifle, both pertain to the metallurgy available to gun manufacturers back then. The pressures of the round you are contemplating will be very much higher than the BP equivalent you are using now. I may contemplate using your planned rounds in a new manufacture gun, maybe even back to a 1920 circa model but nothing before that.
The second reason has to do with the metallurgy of the barrel. These barrels were made in the lead bullet era out of steel that doesn't handle abrasion as well as newer molly steel and harder jacketed bullets are much more abrasive than any lead, even hard cast. Jacketed bullets & cleaning rods have made a LOT of very "nice on the outside" into guns with sewer pipes for barrels.
Do what you will with your gun, after all it is yours but it will last a lot longer (forever) if treated for what it is "an old gun not meant/built to be a hotrod.