my 100,000 mile stock roller lifters
have 2 yrs so far with a lunati 60710 voodoo roller cam-.485 lift and comp 901 springs
has stock oil through roller lifters,push rods,stock rockers
oils both the rocker shafts and through the lifters/PR
maybe thats a starting point for you,not much over stock right there..so I would say thats the lowest you can go performance wize
some one here on the board had some real nice roller lifters with some mods to them that fixed some of the probs with sb rollers
some thing about uncovering the oil gally or something
maybe the will chime in I think it was OU812