D21 Z24 NO Oil Pressure After Engine Rebuild

[Shadow_S14]

Posted this on Infamous, but knowing this Forum is more alive hopefully some of you can help me.
I just finished up my Z24 (Great Grandfather of the KA) rebuild last week and started her up, I test drove it after proper warmup and a brief look over. About 5 mins into my drive/piston ring break in I hear this terrible scrapping noise so I pull over only to hear it coming from the bottom end. So I strapped her up and towed her home. I was curious as it sounded like no il pressure so I wanted to see how the oil filter was, came out fairly dry and through the oil fill whole in the valve cover I could see it was pretty low with oil. Engine was also overly warm, but the gauge read fine.
So this is where I am stumped as I am not sure of what it could be. Any suggestions? Just ordered an oil pressure gauge to check that out, I don't want to take the damn thing out again, but I fear I may have to...
Thanks in advanced Zilvian's!