Hi Ed. You know my preferences in regards patches, etc.
I would certainly test that rifle with the .715's for sure.

My Kodiak .58 had about .008" depth rifling & it used 8 and 10 oz. denim quite easily, with a .574" ball in pure lead.

I measure those denims at .019" and .0225" with my calipers.

Different brands will vary, of course. Joanne's Fabrics in the States has a wide range of suitable cloths.

I would drop a light down the bores to have a look.

A lot of guys that bought those, used phony powders in them, Pyrodex and/or T7.