Do you have a tachometer? If so, it might be possible to come up with an equivalent RPM/speed range in both axle ratios and make a set of stick-on pointers on the tach face corresponding to different speeds. Not a perfect solution, but it might be a good approximation.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
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