What is a good cam upgrade for a 502 MPI. Have header Iron Eagle heads

How much hp did the eagle heads give u with stock cam?

525EFI cam is hard to beat

Griff almost always has great advice, but I disagree with him on the 525 cam. You can make it work with extensive manifold and throttle body mods, but then you are still a generation behind on the electronic end...its just going to have a messy idle with the early MEFI controllers. With custom tuning you can improve things somewhat. With your current set up, I wouldn't go more than a few degrees more on intake and exhaust. With the stock cam, you are already in a small overlap condition; any more and the MAP & electronics will just have a harder time making it all work. I think most here would tell you to go with a new FI system including a different manifold (or even carb). Bottom line: at minimum you need extensive manifold mods with that cam. If you want to see how far you can take it, do a search on Arcticfriends - lots of great info there.