We recently put mechanical fuel pumps on the Aussie bikes , for high flow on methanol,
big capacity bypass valves needed there , used bicycle brake levers and cable setup to control it
Bicycle shop guy was great , spent a bit of time finding levers that were not too obtrusive to mount , and gave us lots of spares to create or repair cables any time
Then we shortened the lever and set up for one finger control like a hot start lever on a dirt bike