I would check the pressure relief built in to the pump. If it picked up a piece of trash that is holding it open then your
oil pressure problem is easy to fix.
I think you will find some foreign material holding open the pressure relief. Pull the pan take the pump relief apart look it over wash it out reassemble and I bet your
oil pressure is back to normal.
In the oh by the way category you might want to consider what some people call an external wet sump. The system uses the pressure stage only off of a dry sump and draws
oil through a pickup that goes through the side of the pan. The pump is easily rebuildable, easily serviceable and in the end quite a nice upgrade to the engine.
I forgot to mention, it looks sort of cool also.
Ed