Shoot whatever is best for you, these old guns are an anachronism anyway (a .338 is probably better today?!!)

My 8 bore DB H&H ball gun is 16ish lbs and not unpleasant to shoot at 10 drams BP (posted somewhere here), good enough to go with Selous to Africa in !878!

I shot a member's single 18 lbs 4 bore with 100 grains Blue dot in Alaska a few years ago at Cal Pappas' shoot and that was a serious kicker but that is what you want in a real life situation

I also have a very lightweight 10 bore H&H Paradox which is a delight to shoot with light loads

Good luck to you and all shooters of these lovely historical guns

TH