The application is:
Marine engine closed cooling. This is for my 7000lb single engine with B3X drive. Cruise RPM on motor will be 3100RPM. Torque is the goal.

Any issues with the Vortec engine in marine app? With standard cam, does it really have any reversion issues?
http://www.michiganmotorz.com/vortec...ent-p-737.html

OR I can go with the Gen V http://www.michiganmotorz.com/marine...991-p-190.html

Which would you go with, and why?

BTW - If I go with Gen V, I am seeking out some better flowing oval ports with a smaller combustion chamber to bump up compression to 8.5 if that is possible.

I guess I can ask this another way. Anyone on here have a 454 with Vortec heads? I heard of reversion issues, but am surprised to hear that would be true in its stock form.

If anyone has reliable experience with the big block (454) and vortec heads, please let me know your thoughts and experience. It would be a great help to me and my partner who are deciding what motor to replace an old stock 454 with.

I don't see reversion being an issue with either in stock form. Now if the boat your putting this into does not have at least 13 inches from the water line to the top of the risers, then there could be reversion even with a stock motor. If you want to be safer and have the room add more height.

The 454 would be ok with your 7K boat, but could just install the stock 502 and have even more power

All I can say is once you go into the Gen V and VI blocks, you run into issues in older boats. No mechanical fuel pump, blocks are supposedly a little lighter in the water jackets, and HiPo parts are a little higher and harder to get correctly.
Example. I built a 496 stroker motor for my 1991 Southwind motorhome (don't judge) out of the Gen V block that was in it. Well, ended up needing a "stroker" oil pan, because even with precision hammered clearances, the rods pinged the pan. Finally found a pan on EBay, however, NO ONE makes a stroker OIL PAN GASKET for Gen V and VI.

Most aftermarket blocks follow the Gen IV big block layout.
As noted above, there is no replacement for displacement, so if you're starting from scratch, not much more to go 502.

Swapped a 454 carbed mag in a formula with a base 496 non ho and converted to closed cooling. Got a pull out with manifolds ecm flywheel ect . Not a bad upgrade and those motors last.

Did you notice any power difference at the throttle? Can you explain a bit more? What size and weight boat? Drive type and prop pitch? Any change in fuel burn GPH or MPG?

Clear your PM box please, it's full

The 496 closed cooling unit wont set the world on fire , but those things are almost indestructable.that generation of fuel system seems to be alot more resistant to ethanol fuel issues too. The 454 mpi often delivers about a 15-20 % fuel consumption advantage over a genv peanut port weber or quadrajet unit. Have not compared fuel burn rates of the 496 to the 454 however

I wouldn't buy a gen 5 reman if a gen 6 is an alternative. the vortecs work pretty good except for above 5000 rpm where you are never gonna go. and the 100 cc chambers are around 9.0 to 1. find an old bravo water pump with the fuel pump on top. or better yet efi.

I would go with the vortec for the roller cam, and better low end torque from the heads