How do you test a turbo??????

[Florida240sx]

Need to know how I can test a turbo to see if it's good.Anyway I can do this at a house with an air compressor. Need to know.Going to be buying a turbo kit and my only concern is the turbo.It's and rx-7 turbo I can get it rebuilt for around 150 if it is bad.Wants 275 for it.Early 90's model rx-7 turbo and idea on specs but mostly how to test it to see if seals are good and how to check it's condition?

[TheOne]

i think 1 of the ways for checking it is by spinnin by hand the shaft/blades and check for shaft play.(as in it vibrates or moves in unnormal ways)