Jon, I don't think the rockers could be machined out big enough to accommodate a needle bearing, but a thinwall bronze bushing is a definite possibility. Use two bushings, one pressed in from each side, to form the lube slot to the spit hole on top. Detriot Diesel connecting rods use two wrist pin bushings with a slot between them to supply the cooling oil spray to the underside of the piston crown. I believe some GMC gas engines also use a gun-drilled connecting rod and pressure lubed wrist pins with a slot between the bushings.
JW, I just bought a Eutectic spray-weld setup that can be used to build up crankshaft journals, and one of the powders that came with it is a "hard-facing" material. That could be used to repair the worn spots, and the shafts reground round with a tool post grinder in a lathe, but at some point, the labor cost would exceed the worth of just buying new shafts.
Jerry