Cody's 440....RRR is off the hook.

On flat tappet lifters for additional oiling, I grind a groove with a Dremel from the oil to within about an 1/8" of the lifter base. Works on sol or hyd lifters, takes 20 min, been doing it for 20+ yrs. There is a lifter bore grooving tool you can buy, does the same thing, but really needs the engine apart to clean afterwards.