I run a Dailey 5 stage on my R3. I have a gear pump section with lobe/rotor suction. It can pull well over 20" of vacuum, so you need an adjustable vacuum valve as well as a safety pressure valve. I too have 1 suction in the valley and 3 in the pan. Bill Dailey ask me specific questions on RPM, use, etc to determine the pump setup and speed.

I have a wet sump R3, but have my pressure feed split, one in the back, but also use the priority #1 main passage on the front of R3 blocks (on the front china rail).

I also have piston oilers installed on my block, mainly for turbo heat, but a side benefit of lubrication. The suction from the pump pulls the oil vapor from the crankcase, so the oilers help lubricate the walls.