Yes, its an old racers trick. If I remember correctly a small vertical groove or flat is machined into the side of the lifter between the recessed area (oil band) in the lifter body and ends a bit (1/8" - 3/16") above the face of the lifter. The goal being to allow a bit more oil to reach the face of the lifter where it interfaces with the cam lobe. I have also seen such grooves machined into bronze sleeved lifter bores many moons ago. Easier to do the groove on side of lifter, though. Its been a long time, but I think the groove was very small. Something on the order of 0.005" - 0.010" deep X 0.015" - 0.020" wide? Some of the cam manufacturers used to sell a grooving tool for this. However you do the groove, be sure to deburr the side of the lifter before dropping lifters into lifter bores.
Anyway...... I'll see if I can get a photo of the oil groove after the Rhoads lifters come in and post it here. Computers are a mystery to me. Wife has a camera around here somewhere that she can put a photo on a computer with. No, I don't own a 'smart phone' and never will. Reckon I've gotten along just fine without one for the past 72 years. No need to complicate things now. :)
