Slant Six Oil light coming on — need a new pump?

Looks like a check valve of sorts. Maybe @slantsixdan will chime in and ejeekate us. As for the oil light, you likely have the same issue my car had. It sat up from about 1980 to January 2019, when I brought it back to life. Same symptoms. Took a while for the oil light to go out on cold startup and the oil light would sometimes flicker at idle when hot. I yanked the engine and trans, removed the oil pan for inspection and there was about a solid 1/2" of sludge in the bottom of the pan and surrounding the oil pickup. I cleaned all that out, cleaned the pickup and Inspected the rod and main bearings. They were actually good, but I have a hoard of slant 6 parts, so I put new bearings in the bottom end, new timing set and a new oil pump in it. I had it out of the car after all, so why not? Needless to say, it solved the issue. That was the 170 original to the car. Although I have a pretty hot 225 in it now, I still have the original 170 on a dolly on the shop floor. I bet something similar may be up with yours. If you get low pressure on the manual gauge, and you likely will, I would recommend pulling it and inspecting it like I did mine.