The dual ganged pot is not anything special and could be found in any electronics catalogue, but what do you mean by non-panel? Ife you have a favourite supplier, we can select from there.
But before going for it, please check out post 11 on that thread, where values were optimised. the best version of the 'Cleartone', dual-ganged design was only fractionally better (ie, the difference is calculable but probably not audible) than the best version of a simple parallel R and C (design C) using a normal pot, so having worked that out, that's what I use on all guitars and I've never personally built the Dual-ganged one in practice.
Got it John...by panel mount, I mean Dual Gangs used on computers/stereos; such as, Alpha-Taiwan Audio Dual Gang pots. I have built it on such with the .0068/150k treble bleed and personally found it to be a superior volume. Could just be a Halo effect. Anyway, the only guitar worthy Dual Gang pot I can find is a CTS linear with detente intended for blend/balance. Ain’t using that. I do appreciate the info provided in your post. Thank you.