Indian creek .555 and 1 5/8th OZ. handloads, have shot 7s, 9s and 9.5s. Also shot the stock choke which is around .580, probably the better hunting pattern, but the .555 is just incredible at longer range and not too much tighter up close.
The 7s were for a couple of states shot restriction, and the 9.5 were the only thing available when I bought shot. All work great but the 9s will be my go to.
Your 8s could possibly shoot better with a more open tube, but that IC .555 is incredible for tight patterns, keep in mind it will get beat up, the wad strippers work well and they are beat to hell in mine, I assume it will cause the pattern to change at some point?
Called Indian creek and they said it was normal, if I buy a new choke it will not have wad strippers next time!
The Carlsons .575 is popular for a good all around pattern.
Mossberg SA/20 thug version.