And now, the devil's advocate enters the scene... or the picture, if you like.
Can you not live with 16 on 120? The image definition from the Rolleicord (Xenar) lens will be superb. In time, you may find a '12' dial (as I did, 18 months after I bought my 'cord Vb with the 16 exposure kit fitted to it), so I now have the two formats. In the more than one year since I acquired the '12', I've used it one or two times - but I use the 16 kit at least once every two weeks. So go figure.
It's all about thinking laterally. 16 on 120 from any Rollei will be, to repeat myself, superb.
The '12' wheels can be found, and when you source one it may be surprisingly inexpensive (I saw one recently on Ebay for A$40). There is also a 24 exposure kit available (I have one but I have to say I use it only once in a blue moon) which will give you 24 35mm size images on a roll of 120 - which may be more shots per roll than you have use for,if you are one of the many frugal Rollei shooters. Quality with the '24' if you expose carefully and watch for camera shake, is very close to what I get from my 1970s era Nikon SLRs with AI/AIS glass. So pretty good overall.
With all due respect to Dan who may be offering you a good deal - think about it, please. (Or respectfully suggest that Dan sells you the '12' dial for a (reasonable) price rather than trade your '16' kit, which anyway is available quite cheaply on Ebay, so they are not exactly rare diamonds.)
We are after all here on Photrio (I much prefer the old name APUG, but that's me) to help one another in such matters...