Thanks for the response everyone! To address a few of the questions/comments:
...how well do the brakes work? as opposed to xtr canti's for example, more or less powerful?
I love the WTB RollerCams (and other variants like the ToggleCam and LeverLink) and have them on most of my bikes. Honestly, I've never owned a bike with V-Brakes --- having moved from traditional cantis on my earliest bikes to the WTB's and only recently getting a couple of modern bikes with disks. The WTB's have most all the power of the disks, but much better modulation if setup correctly. The TC's and LL's are even better than the RC's.
1994? Lovely bike but it looks earlier with that U brake. I have one that I must start on soon. Yours is certainly an inspiration.
The chainstay mount for the RollerCam was the classic and preferred position for this brake by Charlie Cunningham (who designed it) and Steve Potts. It's because the chainstays are thicker and the mount position is better supported for less flex than a seat stay. Although our NorCal mud issues aren't what they can be in the UK, the chainstay position (at least for genuine WTB's) got an undeserved reputation vis-a-vis mud in some quarters.
WTB succumbed to that bad PR on the Phoenix frames -- moving the rear brake to the seat stays in about 1995 (with the less-good position somewhat made up for by the improved ToggleCam linkage on that bike).
If you want a criticism then the tyres look too chunky for a very svelte looking frame.
I agree they look big and extra-knobby especially for the svelte tubes on this fairly big frame. They're 2.1's and are (just about) vintage-correct. WTB introduced these for 1995 (by Fall 1994) to great acclaim. It was their first WTB-branded design after a long series of successful tires for Specialized (e.g., Ground Control).
...You've only mounted the pads for the pics or do you actually ride the Potts with them fitted?
The pads are NOS but aren't just for show -- they'll stay on the bike and get used.
My preference on builds is to use parts of roughly the same condition as the frame. This frame/fork/stem was pretty minty so I wanted the parts to be at least that good. I was fortunate to have a "donor" bike with M900 that could provide many of the parts. Most of the other parts are favorites of mine that I have moderate stockpiles of -- and the pads would fall in that category. In cases where I didn't have the right "minty" part, I went with NOS which on this build would include: headset, pedals, seatpost, grips, and pads.