Won't be too bad. That's a freakin' cool gun.
So heavy I don't think it'd kick bad, my .69 flintlock shoots a 450? roughly grain ball with 100 grains of powder. It's less than a .22 almost.
Goldang though......10 bore....nice.
Samuel Baker of the Victorian era of British empire had a 2-bore muzzleloader....a HALF POUND ball....he named it "Baby" and admitted that it was too severe for even him to some degree. lol.