Holy fuck man, that is some shit. Luckily you had an oil pressure gauge so it didn't happen so unexpectedly, at least you had an idea something was wrong.
Well fuck, sounds like you need to tear that bitch down and see what failed, by the sound of it, i'm gonna say your oil pump or possibly pickup is clogged?
Now what? 300whp Z6 build? Rebuild and reboost the current motor?