Its hard to say without actualy looking at the boat. But that is a well made boat with good engines.
I'd WAG no more than $20k, to make it real nice, if you do a lot of the work yourself. Thats a guess. Your never going to get your money back, boats arn't investments. But that is a boat thats worth putting money into, its well made and you will have something nice when your done.
Personaly I would go with the convertable:
I think its a better designed boat and more usable.
Or if you want something a bit newer the 32 is a nice boat:
Or for a lot less you can get a very similer boat made by Chris Craft:
