My 512:
Promaxx heads CNC'd by the engine builder - 6 pack with diaphragm end carbs-aluminum intake, 259/264 @ .050 comp solid flat tappet-.600 lift, 11.2/1 compression, comp roller rockers, cp pistons, callies crank, 440 source billet steel main caps - 623hp-649 torque on the dyno and was running lean - suspect around a little more hp now after street tuning with wide band and richening up the end carbs - went from 81 jets to 84-86 front and 86-88 rear. All I know, it pulls REAL hard!