Square them up, and anything that's bigger, if you'd like, we can saw it into boards for you... They don't have to be perfectly square, just get the first slab off all four sides and try to keep them out of the dirt...
I thought they were all walnut. Cherry is relatively soft in comparison, at least in my experience. Some friends of mine built their house out of (almost completely) wood they milled on a woodmizer, and their kitchen floors are cherry. The floors definitely have some deep gouges in them; due to the wide boards it just makes them look more rustic (timberframe w/HUGE oak beams in kitchen). Point is, cherry is pretty soft in comparison to some other hardwoods. BUT, cherry sure would look good.
It's true, cherry has been a popular stockwood for muzzle loaders in the past... Maple was too...
I've sold a lot of stock blanks in the past, but i was buying them from a mill that specialized in sawing out Hi-grade walnut blanks, i then resold them through a gunshop i had at that time. I would hand pick every blank myself...
It takes a big blank to make those flintlock boys happy, and i never had a call for one...