yes you'll need to be cautious simply because theres about 5% to 10% of the people selling expensive engine parts, and especially used parts that I can only describe a SCAMMERS, and some guys find out their engine is terminal and try to move it off to be "someone elses headache" rather than accept the fact they screwed it up, or abused it, and their only thought is to regain as much of the original cost as they can and move on.
I posted about the time,
I was at a local engine shop, and the machinist came out and told some guy that was waiting,
that his 400 sbc block walls were so thin that a new rebore was very unlikely to leave enough steel to not have it crack....his response, was , "
ok, just clean it and paint it did sell it on ebay" and buy a new one!