$750 isn't too bad if the motor is really what they say. Can the seller proove when it was last overhauled, reciepts or something like that? Who did the rebuild, again reciepts or something. Ebay may not be too useful because of the distances usually involved. I would try swap meets and the like, also check the stovebolt.com for sale areas. I have seen a few in the freebies sections too. If you are looking into the distant future I will have a 235 that runs great out of a 61 up for grabs in a year or so I think. I'm gonna swap to a 292 or something like that I think. Anyways, good luck.
Kyle