I purchased my 1979 60' convertible late last year, (they're the same model) and every one I looked at had dry rot in the port side aft engine room bulkhead, including the one I bought. The cockpit freezer refridgerant lines pass through this bulkhead, and keep it damp at that point. You can expect to find a rotted area about 1 foot in diameter behind the port generator. On a couple of the boats I looked at, the whole port side aft engine room bulkhead was rotten. Another place to look for rot is the locker on the starboard side of the aft engine room access. The salon steps are located above this locker, and seem to leak into it. You will likely find the "floor" of this locker rotted out. Niether defect should scare you off, all of them have it as far as I can tell, and it's not too hard to repair.
When you go to look at these boats, stick your head down through the forward stateroom sole hatch, and inspect the floor to hull tabbing. Some of the boats (hard ridden ones) have tabing failure in this area, and the whole forward stateroom is floating in the boat. If left unchecked, this failure works it's way aft until the whole interior is coming apart. early boats had an oil canning problem in the forward sections, which should have been addressed by laminating "ring frames" forward of the chain locker bulkhead, and below the forward stateroom floor at two places. Not all of the boats have been thus modified, and you have to check yourself.
There are a few other places to look, too many to go into here, and if you send me a pm, I'll give you a call.
Don't let these minor problems turn you away.
This is the best boat ever!