The PX LZ 5.5 115 in my current gamers (2021 Callaway X Forged) play similarly to the PX 6.0. These guys tested it. https://exactgolf.com/pages/project-x-shafts
Another similar shaft would be Modus 120 X (SS1x).
And, I’ve played the PX LZ 5.0 when recovering from elbow surgery and it is perfect for the 75-80 7 iron swing speed range. I have a set of Ping 710s shafted with them.