I have recently run in my MC21 with a full top end rebiuld.
as for your oil pump question..

I disconnected the oil feed lines at the carby end and secured them with a cable tie so they were both pointing out from the engine (like a U shape)
Fill up the 2 stroke oil reservior, now bleed the oil pump by unscrewing the
small bolt on top.. oil will come out.. screw it back in.
then make up some pre-mixed fuel (i used fuel for my dirt bike mixed at 40:1, but i think 30:1 is recommended for nsr, but i figured a little bit more oil cant hurt.. especially on a fresh rebiuld)
now you can start your bike, running the premix fuel.
Let it idle, reach in and by hand turn the oil pump to full (where the cable from the carb to the oil pump connects) hold it at full and blip the throttle slightly untill the 2 stroke oil starts pumping out the end of the oil feed lines that should be facing back at you (as per the start of my answer)

once the oil is pumping through the feed lines you can let go of the oil pump and watch as your bike idles and you blip the throttle a bit, the oil should keep pumping out the end of the feed lines. (slowly at idle and more as you rev engine)

If all is working, you have now bled your oil pump and feed lines!
you can turn bike off and re-connect the feed lines to carb, drain fuel tank
and run bike again using straight fuel. All done.