I would be interested in hearing what your combination is. Did they just slap canted valve heads over fly cut flat top pistons? That sounds weird but OK. Do you know what the other rods and the mains mic-ed out to? As for the oiling problem (rest assured from what you wrote it's not a fuel problem) the only ways that I can think of for an engine to have pressure that low are, in no particular order;
#1 A stuck pressure relief valve on the pump its self.
#2 A poorly done
oil restrictor system.
#3 Massively oversized clearances on the rod and main bearings.
#4 An
oil galley plug missing or leaking allot. The one at the rear of the lifter valley comes to mind. (I guess this could be #2 as well. LOL)
#5 A blocked pick-up. Could be the pan clearance or just junk in it.
That pretty much sums up what I could come up with. Hope it helps.
Steve