My 2 cents:

The guy is sellin thru the broker cause he can't sell on his own. The engine is the problem. How big - you don't know. Could just need a new head gasket - not likely. Could have a cracked block and need a new block. The motor is the dealbreaker cause the broker won't sell the boat without the motor. Do you want to pay a mechanic to go over the motor, and even if you do - how much will he be able to tell you ? - cause they ain't gonna let him rip the motor apart. The broker will probably decline your offer if it is just for the worth of the hull and lower unit. They will just wait for some other sucker to come along, unless the owner is desparate for a sale. Try to buy from the owner direct for what the broker was gonna give him.

Don't get hung up on NADA values. They are AVERAGE values and they are always low for the v20's that are in good shape and high for the v20's that are in bad shape. There are also BUC values which are much higher and presumably reflect hulls in better condition. Offer the owner or broker the BUC value of the hull, but don't mention BUC.

You could or should do a survey of the hull, if you are not sure of your own ability. A 1993 will likely have water infiltration in the wood core surrounding penetrating fasteners, but the wood will PROBABLY NOT BE ROTTED YET AND YOU SHOULD BE ABLE TO CORRECT THESE DEFICIENCIES AND PRESERVE THE HULL WITH THE TENDER LOVING CARE THIS WEBSITE PROMOTES.

Superclean is a silly term borrowed from used car dealers that means the boat doesn't have dents and dings and scratches.

Good luck.