Stroking the crankshaft to the utmost 81mm will preserve the RPM capability intact. Bores could be brought out to 83mm, but try to help keep it less than 82.5mm. There is no will need to the Formula Atlantic crankshaft. Reject blocks that could require 83mm to scrub up, for sure https://jaredponki.ltfblog.com/26374152/blacktop-20v-4age-secrets