Upgrading shower to Delta trim- can I keep my old valve?

[Dan in MKE]

I'm updating our shower with the single handle Delta Monitor 14 Series Trim (MODEL#: T14467-BL-PP).
Do I have to upgrade the valve cartridge or the entire valve? it's an older Peerless single handle. (The set screw for the handle on the Peerless is in front and the Delta is on the right side.) Appreciate the time and help.

 

[Terry]

That trim only works with the R10000 valve body.
Now would be the time to move forward and upgrade so that you now would meet current codes about pressure balancing.