The problem then becomes installing the electric speedo sensor, cable, etc. I did that on my Jaguar and it didn't work. Now, I'm a better mechanic than I was then so I'm sure I could make it work, but it adds wiring and complexity. I use a GPS for ground speed in the plane, I like the idea in the car, too. It seems most custom builders are going that route too. Please post links to options you like. So now looking at those Koso gauges, I actually really like the form factor of some of their all-in-one units. Gives me analog for the tach, digital on the speedo (which I can accept), in a modern sport-bike-looking thing at a good price. So what's your issues with them from a technical perspective? This one is interesting: https://kosonorthamerica.com/shop/motorcycle-mx/rxf-multifunction-speedometer/ So is this one: https://kosonorthamerica.com/shop/motorcycle-mx/rx-2n-gp-style-multifunction-10-000-rpm/ I've had good success with them too. But I haven't found any that jump out at me and scream "This is it!" Simple and clean, many use them for that reason. Doesn't do it for me though. That's my era as well, but they don't offer any with a GPS speedo, which is a criteria for me.