What kind of documentation for used engine would satisfy you?

Like all the older guys i've got the "rebuilt" Engine, rear axle and transmission T shirts.
For me they are all cores unless i see them' and hear them run' or it's a trusted friend!
It is kind of the same advice I give to people on this forum all the time when they ask what we think a car they are looking at is worth. I always say that regardless of what the seller says, if you can't hear the engine run, you must assume it needs a complete rebuild. If you can't at least drive the car around the yard and test the tranny and brakes, you must assume the tranny needs a rebuild and the brakes need everything. Of course, most of us would do a complete brake job anyway, but it would be nice to know the system at least worked. Also, if you can't start it, you have no idea whether the wiring harnesses are in working order or just junk. I think we need to be as polite as possible when negotiating for a non-running car that "was running and driving great when I parked it", but you are asking for it if you aren't cautious. Also, if you can't do your own work, buy a complete, running car.