How to sell a used engine?

You may get close to the same price by just selling the Air-gap and the Dist alone...
I would explain everything just as you did here to the buyer and go from there.
Are you dealing over the internet ? If so video it running for him.
If you have nothing to hide then you nothing to worry about.

The external parts that I could see were the main reason I bought the car. I have a 340 shortblock sitting on the floor that needs rebuilt and I figured that I could use the heads, intake, and distributor when I'm ready to build it. I never really had intentions of running the engine in anything. The engine is already out and the car hauled off so running it isn't really an option at this point. I am talking to him via PM right now but he doesn't live far from me (90 miles or so) so it would be a face to face deal if he wants to do something with it. I definitely don't have anything to hide with it. It is what it is and I'll tell anyone everything I can about it. I just worry about people coming back calling me a no good SOB even though I've given them all the information.