The eariler bps weren't backbored as they are now. Yes,I went "whole hog" with it,shooting to check pattern and hone a bit at a time as I went.
On steel shot,there's a bunch of shotshells available these days that kick steel shot plumb off the map. Also,with the weight of the 10 gauge bps,it recoils quite a bit less than a 12 gauge 3.5". In fact if you can hold it up-you can shoot em with 1 hand. If you want the ultimate turkey gun-go with 10 gauge. It will be specialized for turkey only,but it sounds like you already have enough shotguns to use on everything else.