Since none of the listed heads are going to do much for you ,I would probably just use the heads that are in the best condition, meaning need the least amount of money to bring up to par.JMWAO

just find some large oval ports cheap that came off a car or use the ones you have if they are not too rotted out - have them gone through all new valves etc, probably cost you about 1000-1200 for a fresh set of oval ports all machine work done with inconel exhaust valves severe duty intake

also about the gen iv heads on gen v there is a special headgasket for this, honestly i would find a good machinist and talk to him about it

This thread started with a guy with a running bb that he was thinking he could do something with by changing to a different set of heads and cam. All this on a heavy non performance type boat with a Volvo duo-prop. Most responses were that it would not be money well spent .Now you are saying he should rebuild some passenger car oval ports with all new valves ,,,and then what .Why spend the dollars .To the OP If your stuff is still together ..run it ..If it's apart, check and rebuild the best set of heads you already own ....and go boating. Spend your dollars elsewhere .My opinion

^^^^^^^^^^ Good advice

X girlfriend ???

My 26 ft well craft cruiser 7.4 MPI needed a rebuild so I installed larger valves and did some minor port cleanup.....these were vortex oval port iron heads. Also I used the HO cam .510/.540 lift and it performs very well......top end up to 51 from 47 using a 24P bravo 3 and cruise speed is a bit higher. MPI Needs tuning if you increase power an I was able to do it using an adjustable fuel pressure regulator and Wide band LM-1....... Mods Did not cost me much as I was rebuilding the engine anyway. I would say if you are rebuilding the engine to go with a str0ker 496 and get a decent exhaust. Don't expect too much improvement in overall performance.... I figure my motor makes about 75 more HP than stock but the difference is not really noticeable in everyday cruising.... TBF