I need a little advice. I have recently purchased a 1985 100 hp johnson comercial outboard. Compression close to 115 psi across the board. I have also purchased a 1986 johnson 90 with a cylinder down, mainly for the power trim. The 90 has a lower unit with a crack in it that has been epoxied and doesnt appear to leak. I've read that the commercial outboards have a lower compression ratio. I have given some thought to pulling the cylinder heads to inspect the deflectors in the water passages and am wondering if i should put the heads off the 90 on the 100? also, my motor has the bigger v6 style case in great condition. Should I run it or would I be better off if i repaired the 90 lower unit and ran it instead? I have access to a TIG welder and am fairly skilled at welding aluminum. Any thoughts?