8MM retainers/locks on 5/16 valves: OK or not OK?

Well....... a customer sent me the heads off his MP 474(?) Hemi crate motor for some porting and a valve job, etc, to go along with some other upgrades he was doing to the motor.
The heads got updated with dual springs and 10* retainers and locks....... he didn’t want the old stuff back, so I put it in a box on a shelf.
Gen 2 Hemis also utilize 5/16” stem valves, and the retainers are 7* like the stock magnum, so I thought I’d see if they fit.
And it appears they do...... but it looks like you’d lose a little installed height.