I know I really like my Rengade .54 and all I have used is patched round balls and on Whitetail Deer it is not lacking. I know there not period correct but it's close enough for Me.
I to wish they were still in business. The price for a peep sight on eBay is nuts for the Rengade I have.
The only thing I did was to put a new and smaller white ivory front sight.
I clean mine with mouse milk and finish up with Balastol for rust protection.
How much are they going for? I have one for my Renegade that I never put on, opened it but never installed it.