I somehow missed this thread, sorry to raise it from the dead.
Until Robert has a PCB for a Dual 808, I'll make some other submissions similar to Bricksnbeatles' suggestions, re 1590A etc.
Not quite a TS, but GPCB has a
postage stamp of a Zen drive, Mini-Zenith. Two of those would easily fit with room left over for a compact Dynacomp PCB (FuzzDog does NOT have a DyanPup), but BYOC has a 1590A dyna-ross (and 1590A TS).
There's other compact stuff out there, if you dig around for it. How 'bout a Muff, Rat and Bluesbreaker all in a 1590BB? Can do!
While 3 stompers on a 1590BB is tight, it is doable if you stick to 9mm pots with Davies 1900 knobs (Davies clones) and kind of stagger the footswitches, outer ones slightly up and middle one at the very bottom of the enclosures face.
BTW...
I aim to have a pedal put together soonish that has 4 stompers on a 1590BB, and I've got BIG FEET! (47)
Do you really want to squeeze 3 circs in a 1590BB when your feets too big?
One never knows, do one?!