[Tinker]

My 53 ford I6 had a large oil bath that was smooth with that "lip", how big is it?. No ribs either. Interested in outcome.

In one way the center looks a lot like my 36 oil bath. The "air diversion" lip on the forward position is a bit telling of a late 40s-early 50s vehicle. Could be a truck or commercial vehicle.

On a 38t the screw release was round. My 53 air cleaner was triangular like you have shown. So in conclusion...