with flat top 2 valve relief pistons 119cc heads .030 over 454.
yur lookin at 7.8:1scr.
dual 2.5" or single 3" exhaust.
with 7.8:1scr. A XE250H cam will be best.
If you have extra money ($500.00US extra) hyd roller cam like comp XE252HR
the hyd roller cam is worth avg 48 more lb ft from 2000-3500rpm.
494 bft @2000rpm vs 538 bft @2000rpm had a 305
have a 357
want a Big Block