600 hp with a slightly worked set of RPM heads,maybe 650 with a nicely ported set is not real hard to do.
For comparison,the engine I had on my dyno today,
505 inch ( 4.350x4.250) Victor heads with minor work,Victor intake,shelf grind Comp roller cam,1050 Dominator custom built 2.125x4" headers made 671 tq/690 hp before major tuning. 715 tq/735 hp after all day tweaking and putting my modified Dominator on.
Keith

www.dunnuckracing.com