512" Built all the B/RB combinations from 431" all the way up to 517", bigger is more and .200" of rod length won't mean diddly, especially on a low/moderate RPM torque motor. Again, piston selection from all the major Piston Mfg's is all over that 451/512 1.32" Compression height slug.

If 6.535" seems short for a 4.25" stroke in a 9.98" deck, remember that there are 10X as many big block 496" Chevies with only 6.135" and 6.385" rods running around.