Ramm,
I have heard of, & seen, inexplicable thrust failures...on many engine brands. I am not sure if anybody really knows the cause. Some engines with GM T400 trans seem to suffer more than those with GM T350. One line of thought is some form of pressure problem in the T400 cooling cct, that causes back pressure & some builders put a restrictor in the coolant line. many theories out there....
I do not think you are properly thinking through this mod. The mains supply that you have drilled into also supplies two rod brgs. Any bleeding off of that supply reduces oil getting to those rod brgs. If you look at used t/brgs, you see wear on both sides. Thrust clearance on Ch engines is 0.002 - 0.010". If the clearance is on the larger side & the crank is away from the thrust brg on the hole side, you have a large 'leak' through a 0.010" gap. The t/faces already get pressurised oil without extra holes, which is probably why no engines have extra holes.
