2 Lines... one each from the back of the heads to either the lifter valley, or all the way to the oil pan. I think most people recomend -6 (3/8" lines) hose.
The restriction is the oil drain back hole in the head... it's teeny-tiny. Once the oil gets out of the heads, it quickly returns to the pan, so there isn't really a need to go all the way back to the pan with the lines.