Interesting thread. I used to have a Zodiac MKII CGT and Yamaha 25D 2-stroke. Great combination.
The transom can be repaired. Previous thread here: https://www.rib.net/forum/f50/zodiac...air-48320.html
Be particularly critical of the boat. Any loose fabric material on edges or seams, sand, degrease and glue. It’s an old boat now and welded seams or glued areas can fail.
Inflate the boat to pressure and check with a soapy water mixture inspecting the entire surface area. The end cones deteriorate too, again can be repaired with the right preparation and gluing temperatures. The rubber end cones are still available from Zodiac.
I’d also replace the rubber parts on the valves (probably Delrin valves), including ‘o’ rings and diaphragms. Again, parts still available.