I thought that I may have seen a similar question before, but could not find it.

I have 74 Dart that I recently bought. Previous owner claims the engine, a 360, to be "Rebuilt". Here's the problem:
When it is first started, oil pressure is about 50-lbs. As it warms-up, the oil pressure begins to drop as the temperature rises. By about 180-degs, the oil pressure has hit zero. Compression is good, as is vacuum and there is no blow-by.

Any suggestions?

THANKS