I don't like that idea, first you never get all the old wood out, your going to drill the crap out of the inner liner, and have to glass it.
A better idea is what hammer said if its that bad. When I did my conversion I wanted lots of reinforcement on the inside.
My transom wasn't rotted at all, but I felt that the bracket should pull the hole transom not just small spots with a washer on each bolt. So I came up with this, Its as strong today as they day I putit in!
And if you do need to inforce it do something like this for the season. I uswed a piece of 3" X 1/2 flat stock, had a guy weld it the same as the bracket. This it during the install.
