Pictures would be of great help to understand the condition. Considering the age of the flatbacks and their foam filled stringers being open cell and waterlogged, they tend to go through a complete rebuild top to bottom. However, its not uncommon for some to reuse the box stringer forms with some reforming, re-foaming, and additional reinforcements (stringer knee ties) due to a slightly different design from how they were originally intended to be used. What are your plans for it? This is a factor that will contribute to what you might spend. You will probably find that the sky is the limit but could have a shop replace the transom and you could finish the decks and stringers. Things have likely changed quite a bit over the past couple years but you could be looking at 20-50k for a complete rebuild depending on what you want done. Most of us on here find the Classic Aquasport as the perfect platform for the shallows but are just as versatile to take a little chop (however, the flatback doesn’t do as well as the 12 degree Classic (72-88 model 222s). My opinion: You already have it gutted? Seems like one of the hardest parts. With grinding being right there on top along with hours of sanding. Why not just keep going? Fiberglass work is actually not as hard as people make it out to be as long as you can either dress accordingly or just be ok with the itch. Hahaha. Hope that helped.