L6-30R with L5-20P Devices
Decided on purchasing L6-30P PDUs, which is what I was expecting. The L520P PDUs were given to me by the partner lab because they also don't have a use for them, because they are also using 208V/30A on L6-30R.
I'll probably save the L5-20P PDUs because there isn't a point in throwing out perfectly good equipment, even if I have no use for it at the moment. Maybe I will request a L5-20R if we need more 125V/20A outlets.