You might also consider using a different type of flat tappet lifters. I know that Comp Cams offers what they call a "camsaver" lifter which puts extra oil on the bottom of the tappet where it bears on the cam lobe. Crower probably has an equivalent type of lifter. I'm not sure how well these work with the non-zinc oils now, but that seems to be what they were made for. Give them a call and ask a few questions. And by the way, roller lifters wouldn't work with your RV cam anyway. You'd have to get a whole new cam to use roller lifters.
