The placement of the grooves coresponds to the area of the lifter face that contacts the cam lobe first. On a clockwise rotation the intake lobe hits the lifter on its "interior" side. On the exhaust lobe contacts on the "exterior" side.
Ok, I'm trying to figure out what you just said. Are you saying that on the same bank, that the lifter bores would be grooved differently because of intake and exhaust lobes of the camshaft on that bank?