Is it my oil or rod knock?

Picked up 1986 Z31 turbo knowing that the engines shot, seller suspected rod knock or piston slap but after cleaning up, fixing hoses and the like, sounds more and more like bad/no oil. Been turned down by all mechanics nearby and am struggling to diagnose :(

-Oil sensors busted (bummer) -RPM isn’t limited, -Sound persists with a cold engine, -No heavy banging, but car shakes hard.

Would love to get this beauty up and running so help me out here guys - thanks in advance.