Your idiot light works on a pressure sensor, not on the oil level. I don't know what pressure it comes on at, though. I would add on an oil pressure gauge since I hate idiot lights.
If the noise is loud enough to hear over the noise of a drill motor, you can pull the distributor and turn the oil pump using an old distributor shaft in your drill. And this is a 2:1 ratio, if your drill turns 1000 rpm the pump will be running at an engine speed of 2000 rpm. This will also let you watch the oil distribution to the valve train.
Oil pumps are very reliable, but your engine is getting old. Usually an oil pump will wear due to dirty oil, and the pressure will slowly drop over time. If one of the gears break, you will loose pressure immediately. And they're not that difficult to replace.
