Have not done that repair
It is good to hear from a fellow T4 owner. I am repairing my 72 Cal T4 but my deck is in good shape. I did have to do some repair around the hatch where the plywood was coming away from the fiberglass deck but that only took some sealant and a few clamps. Where are you located? I am in Ewa Beach, HI with my boat at Rainbow Bay Marina Pearl Harbor.