Rotten transom

[keysv20]

I have a 1984 cc outboard with the cut transom. Today I drilled a couple holes and water poured out. The interior wood looks like pulp and I think is rotten.
when I got the boat the transom had beened glassed over the out side and in the splash well. this did not solve any problem and was a temporary fix. Has anyonne rebuilt a transom on a cc outboard boat? Would like some ideas on how about to go about it. Thinking of closeing in and adding a bracket but im worried about a weight issue. That would get rid of the storage boxes in the gunnels and I would be putting in above the deck livewell.