Man where were you 4 years ago lol, i had the same boat that needed fiberglass patch work, that i gave up on and donated to a school to be used as a sand box. This looks like an interesting project!
Looking forward to seeing the progress. Are you going to epoxy the hull or gel coat? Im doing my 63' whaler and im on the fence to go polyester or epoxy. What fairing compound are you going to use?
I honestly have no idea. Luckily mine was dry as a bone. I have seen several people cut out the floor and dig it all out re foam. I have also wondered if a vacuum pump would work wrap the whole boat in a vacume bag and pump it down for a few days but that would be an experiment .