[blau911]

Assuming we are talking about a 911 normale, and it is truly rust free, I would guess its worth in the mid $20's with the wrong motor. Sounds like a fun car with a 2.4 motor - even a 2.4T. The 2.4T has about as much torque as a 2.0S motor, just not the balls upstairs.
Does it still have the original suspension (i.e. rear non ventilated discs and front non S calipers, Koni's etc)?
Is it running Webbers, and has a 5 speed (not 4 speed)? If so, definitely mid 20's or more. If it had the right motor, and some goodies on it like Fuchs wheels, Cibie hood lights, S brakes etc, it would easily be worth $40's...
Hell, 1966-67 911S's are going for $60k-110k right now. And the really clean SWB 912's are now selling in the 20's. A really clean 911 normale should trade somewhere between that.
Just one person's opinion. Would be interested in others as well.