Answering the question above. Changing from OMC to Alpha One cutout meant completely covering the opening but since I was replacing the transom plywood, that wasn't really a problem for the new wood. The bigger issue is layering in fiberglass on the outside of the hull to fill in the hole and then gelcoating it. So, not bad at all if you are doing the whole transom. I have the factory tool for cutting the keyhole and drilling all the holes so that was pretty straight forward. Biggest problem there was saws getting dull quickly.
