Sorry to say it, but the guys above are probably right...dollars to donuts every bit of structural wood core in that boat are rotted out. You need to get a drill and drill into the lower part of the transom from the inside of the hull and check if that's rotted out. If there's a miracle and it's solid, you can shoot some marine epoxy in the hole and call it good. I wouldn't go ordering glass or resin just get until you know the scope of work by first removing the decking and grinding back bad glass, because odds are you'll need a LOT more glass and resin than you'll initially think you will.
If you're replacing structure, which the deck usually essentially is, you will need 1708 to tab it in. If you need to replace stringers, bulkheads, and transom...you'll need a lot of 1708.
My opinion, go get core samples of the transom and stringers before you do anything else, generally the lower the better...water rots boats from the bottom up.