[willy]

Welcome aboard, just so you understand what you have there a few points. Your transom is all wood with fiberglass on the inside and outside. Also the stringers and floor supports are wood enclosed in fiberglass.. My boat is an 1985, it was originally like yours with a sea drive.
The comments made to you about repowering refer to the fact that your boat is one of the most, if not the most desireable for repowering with a armstrong, gill or stainless marine motor bracket. For two reasons, one your sea drive was sealed well from the factory and as long as some idiot did not drill holes all over it and not seal it correctly you will fnd the wood inside the transom will still be strong and dry. Two the hole that was made for the sea drive is a small one, approximatly 6x7". This is good because it did not allow water into the wood and it sits pretty high and because it is simple for you to close that hole and seal it when a bracket is installed.
There are several guys who have done just that on this site and recently too. Makes for a sweet V, not that the other power versions are not, everyone likes something different, thats why they made blondes brunettes and red heads. ;D I personally like my set up but would have been very happy with an I/O or standard outboard set up.
Good luck with it you have a lot of potential there for a sweet boat