Some questions come to mind if going with roller lifters in a Y,
1.) the lifter bore is round and has no provision to keep the roller aligned with the cam, what would need to be done, we wouldn't want the roller turning sideways on the cam. in order to place keepers on pairs of lifters the lifter would need to be much taller to stick out of the block and require shortened push rods.
2.) The lifters turning rotate the push rods, with rollers they would not turn, would this accellerate wear and require more frequent valve adjustment or would they wear less and require less adjustment.
Just some thoughts to stir more minds

55 Vicky & customline
58 Rack Dump, 55 F350 yard truck, 57 F100
59 & 61 P 400's, 58 F100 custom cab, 69 F100, 79 F150, 82 F600 ramp truck, 90 mustang conv 7 up, 94 Mustang, Should I continue?