Finished wiring up the clock, and it seems to go fine. The video is pretty boring, I know, but I had to have some evidence of how I spent the past few weeks. :-) The tubes do have uneven brightness: the third one seems to have a blackened grill, and is dimmer even though it has a smaller anode resistor. The fourth also has a smaller anode resistor, making it a bit brighter than the first two.
Apart from some fiddly soldering with a fat wedge tip, this came together fairly easily. The next thing to do is sort out the software, rig up a case and see if Andrew T will part with another ts7260. I've yet to try out John Taylor's power supply, and am hoping I can run the whole show off the 5v the ts7260 is supposed to pump on the LCD port.
As for numeral systems, the answer is a big no — there are heaps of natural-language numeral systems in common use, even now.