As previously stated, the REV 2 does not have CV out, so you'll need either an external MIDI to CV converter a conversion unit in the Pro One. I don't know anything about the Kenton unit, but it is certainly an option. I used a unit from
http://www.musictechnologiesgroup.com/ which replaced the CPU. I like that it included some expansions onto the sequencer and it's install is pretty straightforward so long as you aren't afraid of soldering on the Pro One's board. Once in it works great.
The keyboard in my Pro One was dead (one of the membrane types). Found this guy on the web who sells a complete Fatar replacement keyboard. It was pretty much plug and play (I think you have to add a couple of mounting holes to the bottom of the case):
https://techsmechsvintagesynth.com/home/tm-2-pro-one-keyboard-replacement-kit.htmlPretty much transformed my Pro One. Great action and consistent note triggering! That said, if your Pro One has the earlier J-wire keybed it can (and should) be fixed. The later membrane ones are hopeless once the contactors die and can be tossed.
Good luck!