Something else you might consider is to put a "T" fitting in the block where the original sending unit was screwed into and run both a mechanical oil pressure gauge and the original "idiot light" oil pressure warning light. Use a brass or mild steel T fitting with male threads on the long end and female threads on the two short ends. Screw the long end into the block, then screw the factory sender into one of the female fittings and the connection for the mechanical pressure gauge tubing into the other female threads, then mount your gauge in or under the dash, whichever works better, hook up all the wires, and you're in business. That gives you the best of both worlds, you have both an oil pressure gauge and a warning light. I've done that to all the cars I've owned that didn't come with a factory oil pressure gauge.
