Dual oil pressure/water temp quage

[PH4]

I have the dual guage which I wish to switch from my 1962 to my 1972. Has anyone done this before? Do I need to order a plug/part to put in place on 1962 where I remove water temp hose that goes into engine? Should I switch out the guage cluster also? Advice appreciated.

[PH4]

To clarify, I have both the early IIA main instrument cluster and the Late IIA instrument cluster (the 72 is a IIA CKD, not a III).