I have a 1986 Lotus Challenger SX that I fixed up and started to ride it a lot this summer. It originally came with stem friction shifters.
I have gotten used to the shifters but I feel like downtube shifters are a lot better.
The frame does not have existing mounting points for the shifters, but I have seen on ebay used downtube shifters that are attached to collar style clamps, and you fit it over the downtube and tighten down.
I had an idea was to cut off the cable housing holders that are welded on to the downtube, sand it down, and then put the downtube shifter collar in its place. Would this be a good idea in practice?