If I was truly interested in buying an engine for that price especially if it belonged in my car and not trying to jerk the seller around I would travel to see it in person and tell the seller up front that I want a head removed while I am there to check for decking marks under it. Also, for that price I want to hear it run and if all looks legit (casting, VIN, broach, etc...) I will then hand over the money.
Just my opinion,
Mike