512 cam selection, what do you think of these options.

I ran the one-step-bigger Comp XS (.540/.560") solid cam in a friend's 446" RB and it worked really well. We did run 1.6 rockers on the intake for .576" gross lift. I think it would work better in your 512" than the smaller one you listed. That big stroke is gonna want more in my opinion, based on the results we got with the 3.75" standard 440 setup.