gcf, you can get as complicated about this as you wanna, but I'm a "load some up and see" kinda guy. In general, you want a bullet that is a hard push fit through the cylinder throats.
I very rarely shoot full house magnum loads and when I do I want them gas checked and hard, 18 bhn+. That's only time I want real hard bullets. Most of my shooting is done at about 1000 fps plus or minus a couple hundred fps. For that, plain base works fine, and WW+2% tin aged at least a week (c. 12 bhn) is the right hardness. Very hard bullets tend to lead at moderate pressure and velocity.
My approach would be to load the fattest bullets I had available and see how they did. I don't go messing with slugging and measuring until I know I have a problem.