You realize that if it doesn't start, the head, tranny, anything could be screwed up right? How will the buyer check? Can't do a compression check, if it doesn't start, can't really do anything...you might want to either offer them some sort of warranty that the engine itself is fine (as stupid as that may sound I doubt anyone will buy a car that doesn't start and the seller says it's something small) or you might want to get it fixed. Just my .02.