What will you do with the hole in the base (LH side)? With my Mustang GTS, I just stuck a square of tin on the inside with liquid nails and then apply Selleys Knead It over the top.
I also examine carefully for fine cracks emanating away from the hole and if there, I drill a small hole (about 3mm) where the crack(s) end. that stops them from expanding any further in future.
