I believe the R and R1 needs the same precautions to the lifter bores as a small block. In other words to ensure no excess loss of oil pressure you would bush the lifters or tube the block. One look down a lifter bore will tell you if there is a big hole or not.
Also check to see if other oil mods are needed like the stock small blocks from filter up through rear main cap, Main saddles to lifter galley, ... Not sure if the oil galleys on these were any better.
