I don't think the auction folks will take kindly to you removing injectors and/or glow plugs to do a compression test.

Try to start the engine with the glow plug harness disconnected from the relay. If the engine starts within a couple of cranks and there's only an initial puff of whitish gray smoke that smells like charcoal lighter fluid, and the idle is smooth and even, compression shouldn't be a problem.

I don't think this is the only thing you should check but your resources are limited at an auction lot.

Sixto
91 300SE
87 300SDL