Question about buying a used engine

[sandking]

I am looking at an engine tomorrow that does not have a starter or an alternator. Not a big deal there, other then that, it is complete with a harness, computer and other accessories. But what should I look for if I cant check the compression or hear ir run, besides a visual inspection. It is supposedly a low mileage 6.0 LQ4. I am working on a trade, so it's not cash deal. I know I can check the oil, but anything else I can do? I don't have a bad feeling, but you never know. Thanks for any ideas!!