hmmm...not too sure, I haven't done it but now I can't remember who had suggested to try it(but definately was a Buick guy)...It wouldn't need to be very deep, maybe .010-.015 at the most and probably just as wide...but I wouldn't go across the whole bearing, but maybe 2/3 of the way across and at the 6 o'clock position with the engine upright...
The thing about drilling the hole in the galley plug sounds like something that would be done on a Chevy since their oil pumps feed the mains and rods first and the lifter galleys last...Buicks are definately a different animal...
Did you say you had the hi-vol pump on there and then when you tore it apart, you noticed some wear to the cam bearings and block face??? If so, I would not put the hi-vol pump back on, I would put the std pump back in(which is what I'm doing) and put it back together and not worry too much about it...Personally, in my case, I think that running the hi-vol pump put too much pressure on the cam sensor drive gear and drove the cam back into the block...I also saw some wear at the 6 o'clock position on the cam bearing on mine too...Going back to a standard pump is something that I think will help me out, much like the 455 Buick motor should not be run with the hi-vol oil pump because it will DESTROY the front cam bearing and/or the distributor drive gear...The BB Buick just don't need a hi-vol pump, like the V6 motor, IMO...Live and learn the hard way, I guess(The std 455 oil pump uses the same length gears as the hi-vol pump gears for the V6/small V8)...The Buick V6 pump is the same pump that was used in the small block Buick V8(300, 340, 350) and was more than adequite for the small V8, as long as the bearing clearances and the oil pump clearances were okay...But on a fresh motor with tight clearances and a good timing cover/oil pump clearances, a standard pump will supply more than enough oil pressure and volume for a "little" V6...Just MO...