For the U-brake, I had one chainstay mounted and it eventually snaped at the boss join. I think you will be fine as there is a brake booster fitted. BTW the boss position of a U-brake relative to the wheels are not the same as cantis.
Yes, I don't want to bother welding on canti mounts unless it's really necessary, which it sounds like it isn't.
I would have reservations about the hub technology, and would favour a Shimano cassette and freehub
I'm sorry I wasn't clear - the hubs are Deore Dx w/ 7 spd freehub. The hubs look in great shape; I plan to keep them & install a modern 7 spd hyperglide freehub so that it's easier to replace casettes. I assume 7 spd is still easier to find in developing countries than 8+.
STX is not bad kit either., but invest in either Surly steel or Blackspire DH / TA / Middleburn chainrings on it instead.
For sure. In fact the current rings on the STX chainset are cracked and rusted, so although I'm a cheapskate there's no temptation to cut corners here!
Koga has a long history in touring if you check that loaded link I posted koga is a weapon of choice for quite a few
That's part of the reason I went for this frame. But the modern version of the World Traveller (their top-of-the-line trekking bike) is overpriced & IMO unsuitable for really remote travel: aluminium frame, proprietary headset, hollowtech cranks.
Vintage World Travellers are almost impossible to find, while there's a glut of vintage Terra Runners. Got mine for just 60 euros. Seems like people who bought high-end trekking bikes tend to keep them for life, while high-end mountain bikes are regarded as disposable.