Project Frog Princess

That's cool. How would one connect the speedo? I would not care about the signal lights as I'd do them like the customized version I showed.
I do like how aftermarket gauges provide other functions including warning functions. Still undecided.

Anyone hazarding a guess on the "bushings"?

The speedo is still a mystery to me as far as doing it in reality, but on paper, it works, and you'd basically have to make the cable yourself. I've been reading up on it, and nothing from the miata specifically, but I think it can be done. If all else, you'd use the sender on the diff to power a newer cluster speedo along with a vss. I'm still working on it. There are a few gauges I've seen as well with warning functions, but isn't that the idea behind putting a real volt meter, and oil pressure etc?