I've got a 1999 502 415 MPI that I bought 4 years ago which had a reversion problem. I ended up buying another engine and no longer have a need for this.
The engine still has only 90 hours on it, I did not have it rebuilt. What would be a fair price?
Thanks!

is it a full motor with efi or carb or a long block

Complete engine, MPI (Multiport Injection) The engine has been stored indoors, everything else appears to be in great shape.

Does it have the accessories and wiring?

Yes it has all wiring and accessories-starter, alternator, MPI unit, etc. Mercury replaced this engine with a brand new engine. I bought this engine from the dealer.

You say that it had a reversion problem. What was/is wrong with it?

The exhaust was leaking water into the engine causing the oil to become "milky". I'm not a mechanic but I understand that the heads would have to be gone over along with the bearings (to make sure they are not rusted).

If the cylinders aren't ruined i'll give you $2500