My boat is wired with a 14 pin harness, i am repowering with a 500 HP which takes the 10 pin connector. Can i simply cut the 14 pin plug off and wire the 10 pin on?? Will the colors match up or is it not that simple??

there are adapters out there that connect the two, look around online, I used one when I put a newer 496 mag HO in an older formula. I think I paid $ 60

Ok this is what you are going to need.
84-892444T02
-reverse adapter that allows installing an older (10 pin) engine into a newer (14 pin) boat.

If you had Smarcraft you are going to need some extra connectors (Merc standard plugs) If you have DTS ... You might need a new dash + more ..