Those Rochester twisty gauges look like the ones used on older lawn mowers. They were built into the filler cap. I had one on a Sears mower back in the day. Even some plastic outboard motor tanks had their version. they worked pretty well.
But that reminded me of the earlier gauges used on steel Johnson and Evinrude outboard motor gas tanks. Those would be easy to "calibrate" by modifying the lever arm.
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Chuck.
“Any suspension will work if you don’t let it.” - Colin Chapman
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