Best cab for Tannoy 12"

Ok, y'all.  Here's my problem:
I can save a lot of time by admitting I'm a Tannoy fan. Got spoiled a LONG time back with a pair of 12" silver
Monitors in Hartley "Boffle"cabs(!)   I want to buy another set of 12's, tho' a properly restored Silver set is probably
beyond my means. So, we move forward: Reds, golds, ?? I'll find 'em.
I have a space problem, of sorts. Can't accommodate cabs wider than 18" max and must be placed no further than
6" from the back wall. Walnut much preferred.  Earlier 12" Tannoy cabs look puny and no style whatever.
Sonics? looking or the best bass extension possible. I'm aware the 15s extend nearly 1/2 octave lower in the
factory cabs, but with a custom cab and proper, extra-high quality crossover re-builds, honest, defined info
to 28 hz + or - is doable.
Where do you guys think I should go for a proper cabinet - refurbished factory, or custom? and if custom,
whom should seek?
Many thanks, in advance for some expert opinions!