do you think these Shimano Downtube Barrel Stops in Tree Fort Bikes Cable Stops wouldn't work?


note it's the curve of the tube not the square boss that keeps these aligned

they have a big round hole inside, and are designed for square-section bosses - I bet they'd clear what you have.

Do you have a photo of your DT braze-on?

I would think it has to be similar to the boss (plate holder) for these thumbies, and I think the Shimano barrel stops would clear it