I seem to remember that the #1 and #2 bearings are 1 dia and the #3 and #4 are slightly smaller? When I got my set of TA Perf cam bearings, 2 of them would slip right through the #1 hole, while the other two were an interference fit there. It seems really odd to me that the #4 bearing would have 2 holes in it. And if it was a left over #1 bearing, and the #4 hole really is smaller, then someone must have really crushed that thing to get it in there!
Whatever the case, a problem in the #1 cam bearing area can starve everything else of oil. All the oil to everything (except the turbo) passes by the #1 bearing. If it is hemorraging oil there, expect all the rods and mains and everything else to see less oil. One guy here went through 3 rebuilds before they found his problem, oil leaking between the block and the #1 bearing. They had to hone out the block and I think fabricate an oversize bearing to fix it.
John