variable duration lifters (rhoads)

i admit, it's for my 302 ford....my daily driver 68 mustang has 1/8" crankshaft endplay, so i ordered a bunch of parts for a better build on another 302 to drop into it, and already had that new cam on the shelf. I thought it was a bit much for the 302, so i got the Rhoads lifters....but now I need to send them back, i suppose.
They'd be good if they fit the 400 in the cuda, because it only has 8.5:1 and a purple shaft .509 cam. they would definitely improve driveability in it, IF i wanted to improve driveability.