What to look for when buying an engine?

[95AWD6Bolt]

I am purchasing a sopposedly recently rebuilt 6bolt engine. What should i look for when buying it. I was thinking about a leaddown test, i have an air compressor but dont have a leak down tester. So what else should i do and does anyone know anyone in south jersey that will rent a compression tester?

 

[LaN-]

you could either buy a compression tester (30 bucks), Or make a leak down tester (30 bucks).

 

[95AWD6Bolt]

Just to clarify i cant do a compression test because the engine is not in a car. If i can do a compression test out of the car please let me know.