Unless you have issues with the way it runs, i would leave the motor where it is. Typically as Rickk mentioned, the cavitation plate is at the same level as the bottom of the hull at the transom. Regarding the fuel tank coffin, not sure why one would scrap it out of the boat. It serves the purpose well to keep the fuel tank off the bottom of the bilge area a few inches and out of the elements. The hatch setup is nice to get to the tank in the future if and when it fails.