Keep it original?

[wgscott329]

You might be able to skim off the top layer of glass right where it makes the turn up to the sides of the liner. Take out the bad core, and then make your new floor to fit over the bottom layer of glass remaining. You probably need to take all that potter putty off. Its a pain. Moving the tank forward probably won't lift your stern all that much, I would bet 1/2" or less. most people raise the floor about 2-3" to solve the transom water issue. If you want to do this you'd have to flatten all the potter putty anyway to be able to evenly heighten the stringers, and your floor would be hitting the liner 2-3" higher, so the lip you left around the edge would be irrelevant at that point.