360 oil psi dropped all the sudden

You say you used a stock replacement pan, I'm guessing you didn't put any kind of baffle in there? It is very possible you uncovered the oil pickup going down the drag strip and possibly rashed the bearings. This is why it's important to either weld in a home-made baffle when using a stock oil pan or go with an aftermarket deep-sump or baffled pan when racing.

EDIT: HV oil pump would be a good move esp. if you are rebuilding it with wider bearing clearances. Get one of the redesigned oil pump driveshafts as well since the stock ones are known to break the tip off when put under extra stress of HV pump/thick oil/high RPM.