I would check out the way the different rollers are gravity lubed and pick the best lifter oiling that way. You can add some oil by grinding a .002 deep flat, inline with the sides of the axle, front and back, similar to the Crower "Cam Saver" but, all the way, from end to end. The cam savers just go to the lifter recess, to squirt pressurized oil on the cam.
You could also, grind a deeper but, narrower groove, for more oil.