TOPIC: replacing wood reinforcements on transom?

Ive got an old alumacraft 12 foot runabout. I dont know if these came with plywood in back, or if some body else made the wooden parts. What i do know is theyre rotten, and need replaced. These were glued and screwed. The tin transom is pretty rough with glue, cement, gooe screw hole dimples, crud bumps bruises...

So, how do we prep and secure a plywood transom properly with such a rough start? What about gluing a rubber gasket between the wood and metal to take up the gaps and make a better seal?

I replaced what I thought to be the original wood on my 58 Alumacraft a couple of years ago. It was not glued on at all. There was a thin sheet of cork acting like a gasket between the wood and aluminum. I ordered a new sheet of cork (from ebay I think) cut it to shape and put it back in the way I found it with new Plywood.

Thanks! Im thinking my tin boat didnt have a plywood transom, but it seems like a good idea. Especially because previous owner "trimmed" the metal transom support. Not too bad tho. Cork it is then.