Question about Kwik poly

[Striper80]

I have an 82 Grady White Tarpon(tournament) 190. I pulled the 89 110 V4 to put my 96 Johnson on to test it out. When I removed it I decided to pull the aluminum trim and take a look at the transom. I wasn't happy to see that it was a wet and seemed to be rotten. I saw someone on here mentioned using quick poly on a transom before. I was just wondering if they dried it out first? My newer motor is a long shaft so I have to use a jack plate so it's going to have more leverage on the transom. When I tilted the original motor up all the way and jumped up and down it didn't flex but now I'm a little worried. I was thinking of trying the quick poly and putting an 1/8" thick aluminum angle over it to re-enforce it.