Well, that option is starting to look more attractive than a rebuild. Did you go for the GM 502 HO?

This is what my builder put in my engine
 

J&E/SRP PISTONS
Part #99-139482FTF

502 mag mpi bore .030 over

$624 this past February

Alex: My boat is a twin so I needed an exact replacement engine so I did not buy the GM 502 HO. I'm not sure it has the correct cam for marine application. I bought a 502 marine engine. I cant remember who from at the moment. It does have a roller cam where the other engine still in my boat has a flat tappet cam but I cant see any difference in the way they run.
I have seen these engines for sale new around 4500.00. So if you are going back stock it might be the best option. Sometimes the time of season may be a factor. I didnt want all the down time waiting for the rebuild. It was the middle of summer.
Jerry.

Thanks, found them in the SRP catalogue under flat top pistons, -3 cc 'dome volume' indicating they're just flats with a valve relief.
That must be the piston they (JE) mentioned in their mail.

The 502 HO does not have the marine cam as sold from GMPP. The engine also comes with the long circulating water pump and flex plate for auto tranny but these are simple items to correct.
The history though goes like that the 502 was originally intended for marine use since it has not been factory fitted in any car. Later of course it has found its way down under some hoods as well.