i would do a compression check before buying any secondhand engine.
find out who built it, if it was a reputable shop, then it might be good. if the guy selling it says he built it, or a buddy built it... then you need to ask lots more questions. he should know the build inside and out, what exact parts were used, etc. find out what parts are still stock and what is not. were the cylinders bored out or honed? did they replace the timing belt, water pump, oil pump, etc during the build? i would ask if it was ever dyno tuned, or tuned at all for that matter. all that being said, if you are looking for some sort of very reliable daily driver motor for you civic or whatever... then i would just stick with a basic GSR swap, stock motor.