What main bearings for a high performance engine?

Thanks for all the links guys. I'm still not sure how oilng mods will help my engine though. When I strip it down after it's been running for a period of time I don't have a lot of wear that would suggest insufficient oil. My main issue is oil pressure. For some reason I just can't seem to get decent pressure in this engine. I don't feel that changing the spring in the pump to increase the pressure will help either because as far as I know that's a pressure relief valve and it has to reach a certain pressure before that opens. I don't think mine's even reaching that pressure.
Tell us about the build an maybe we can help with oil pressure.
Some of the guitar Jones mods like tubing the block and restricting the flow to the cam bearings and rockers help boost the oil pressure. Need to know more about the build.