How do you know, did YOU inspect them? ..... so I'll retract and re-state:
Ok, "the" factory J heads will support 350 hp easy. To the OP: IF your heads are junk, rusted, cracked, missing valves, cut in half, used for a boat anchor in a salty ocean, then "YOUR" heads may need to be replaced. But, the factory J heads will easily support the 350 + HP goal. :)
