Yes I know that this may sound stupid, but I wouldn’t pay a more than $500.00. Yes but there are a couple of red flags for me. One, it’s been sitting a hot environment for 20 years. It would surprise me if the oil seals are dried out and it will leak once you have it installed. Same issue with the carb and fuel pump. I don’t know which carb is installed on that engine, but if it has a diaphragm I would be replacing it before installing. Those engines came with and without fuel pump, again is it mechanical with diaphragm? That being said, I’ve worked on dozens of those engines on Toros, construction equipment and RV generator set and have found them to be extremely reliable and I would purchase it in a heart beat if I had someone looking for one. Personally I would say you have a 75% chance that this could be a steal.