I'm looking for suggestion on replacement heads for a 502 mag mpi. I'm not interested in building horsepower, so as close to stock is preferred. I have gotten info on the World 310's which should not require ECM changes but wondering if there are other manufacture? We run a lot of salt water in this area and don't want to have issues. Any input would help with the final decision.

What's wrong with yours??? Rotted out???

yes sir... last owner must have left the salt water in the motor after every run including storing for the winters? the exhaust valve guides rotted through and cracked causing water to get into the cylinder. time for an upgrade....

There is now a direct replacement for your stock heads. A company is now producing a replacement head cast in USA. We talked to them at PRI and they are now available. Contact JimV for the info on them and where/if he get them for you.

I would be concerned about the blocks then as well. Might be beter off to look for a set of fresh water take out engines.

I agree - especially with the Gen V/VI blocks, since the deck is thinner than the old Mk IV blocks. Might be time to cut your losses. Is this a single or twin?

Jegs and summit sell pretty inexpensive gm square port replacement heads

The problems with this boat started 2 years ago. The #6 exhaust valve guide rusted through inside the water jacket. It allow water into the chamber and hydraulic the cylinder. Well long story short the cylinder cracked and I had to replace the block. The valve guide was a hard issue to pin point. Not something that usually happens.

Since the block is replaced, I would just look for a used set of fresh water stock GM rect port heads. They can usually be had for $400-700 a set.