If u can get take out 502 at a great price go for it ,,if not I would turn those 454 in 496 ,,,and cam it rite

thanks Guys - good stuff. Compression-wise I guess I need to do more homework. thought the aluminum heads would let me run a couple more points of compression but that assumption may have been 93 octane based and I can't count on anything higher than 91 at the docks where I buy gas. 9:1 with big loads is safer then so be it.

What gen are the blocks? Sure, you can put gen 6 heads on a mk4, but... anyway, with your rpm range you might wanna consider L29 heads. Small chambers get 9:1 with flat pistons. The heart shaped chambers and swirl ramp in the intake ports add effeciency but are limited to about 5k rpm. 454 to 502 is 10% diff in displacement. I doubt you will feel 40 hp diff. Cast crank is no weaker than forged...at 5k or under. 6500? You gotta have steel crank. You do want forged pistons in the long run. The stock L29 heads apparently come with inconel or equivalent exhaust valves. And they are cheap and easy to find. The L19 is the same motor with steel crank and forged pistons, heavier rods.

interesting. existing ones are GenIV but not really planning to reuse them ... prefer to start fresh and swap em out over a weekend on the dry.