The Cinelli hex key that came in the Paramount owner's kit was a 7mm in the days when the Cinelli 1A stem had a standard hex nut on the bar clamp and a 7mm internal hex on the expander. We guarded these jealously in the early '70s, as it was about the only source for this odd size. If your Paramount Tool Kit was missing this wrench, go find the guy who built it up. It's probably still in his toolbox. In '75 or so, Cinelli went to dual 6mm internal hex and the included key changed to a 6mm.
On clamping frames, I still have my Park shop stand from my wrenching days. When I am too lazy to fiddle with the seat post, I wrap one of those thin, lycra surfaced, rubber mouse pads around the frame and apply just enough force to hold the frame in place. I always wipe the tube to remove any dirt, and I never clamp to anything but paint--no decals underneath. It's just not worth it. The mouse pad works great, but keep the fabric against the frame and don't leave it clamped for days or weeks at a time. If the rubber is left pressed against the paint long enough, you can get some extractive bleeding which will ruin your day.
For a quick derailleur adjustment or on-the-bike wheel truing, this procedure works like a charm.
Steve Barner, urging you to never, ever clamp over a foil decal, as I did just once back in 1971, Bolton, Vermont