I think RXmangriff found the last existing NOS oil pump, in Germany! That's the only one I've seen lately.
Mine has 130,000 miles on it, and until about 110,000 it kept up fine. After that, I pretty much had to stop using 10w50 oils in warmer weather, as the idle pressure would fall off quite a bit. It runs fine with 20w50, and almost as well with 15w50 synthetic (diesel oils). I've gathered a batch of used pumps to see how much they wear at 8k, 20k, 40k and (unknown miles but very abused)k miles, to see if they can be remanufactured. I should know by Spring or so: I've got too many other irons in the fire at the moment.
One thing I have found: the O-rings inside deteriorate and the O-rings that seal to the oil pan flatten and harden. Both begin to leak. The shaft seal, likewise, but I think I have replacements for all of these, now. So, I have to build up a test oiling system, replace the seals in the pump, and see how much improvement might be there. I'm also going to attempt to dust off the body surfaces and reduce the tolerances inside to see what that does to one.
The biggest problem with racing these in the past was in the selection of the weight of the oil, not the lack of pump pressure. Too many 'racers' ran with 10w-something oils because they believed it "created less drag". In truth, at racing temperatures, the 20w50 was not enough, and straight 40w did a better job, outside of needing some preheat to avoid cold-start cam scoring issues. If you put a gauge on these engines, then switch between oil weights, you will be very surprised to see the pressures that pump delivers. It's highly tolerant of wear, and surprisingly durable over time. I wouldn't worry about it, if I were building up an engine. If the issue bothers you, just install an oil pressure gauge in the manifold on the back of the cylinders to put your mind at ease. I usually find, after a rebuild, that 30-40 kicks of the kickstarter will put out the oil light as it fills the engine's system. That switch takes over 30 PSI to turn off when cold: that's a lot of flow from a kickstarter!
