If they are close to you, run down and check out the shop. If not, and you have doubts, can you find the same deal close to home or one about the same price that would make you feel better?
That is always the tough thing when you buy/sell a motor. I have my motor listed in the classifieds but I know the questions I will get and they are genertally questions that the buyer asks trying to find trust and confidence that they feel they are getting a good motor. There are too many scammers out there and a motor is one of the easiest things to pass off on quality but in reality it is junk.