I just discovered your post. What a beautiful rifle! I also prefer .54 cal, even .58 cal, but a fifty should be a fine weapon. You'll just need to add appropriately sized ammo & patches to your inventory.

Here's another angle you might consider: advise "Grumpy" of the vast & continued shortages existing in the modern weaponry field, & folks may likely be compelled to return to muzzleloaders as the only viable firearm. It's worth a shot (pun intended).