I've done quite a few stock 500 efi Whipple setups. The rotating assembly is most likely fine with those hours( if the engine's out I'd check bearings anyway), but definitely go through the heads and do a valve job and springs. Dustin Whipple has a great tune for that engine in stock form that should be turn key. But, if you change cam, heads, etc. It will need to be fine tuned by someone. Make sure he knows the altitude you are using the boat so he can set it up correctly. A stock 500 EFI makes well over 700 hp with the Whipple package.

Bob Lloyd
Full Throttle Marine