I've done this with my '82 Trek, thought it'd look neat. Let me dig up a picture. I used these which I had bought for another purpose, but they fit snug in the TT cable guides as cable stops. The previously mentioned inserts above didn't fit in my cable guides (also had a set for another purpose). No significant improvement or deterioration in braking.
https://jagwire.com/products/small-p...nless-end-caps
