If you are really trying to keep cost down, consider looking for a suitable electronic speedometer in the boneyard. Tim Moore found this decent-looking 85-mph speedo. The hassle is supplying the speedometer with a proper calibration signal. The connections on the back of the speedo include 12-volt switched power, ground, and the signal input. We test-fitted this in a ’65 Chevelle instrument bezel, and it fit quite nicely. The problem is finding an accurate, matching tach.