Not that easy in most cases. For some reason most cars have different resistance readings on the gauges for fuel and temp and the gear / diff / wheel size ratios are never the same for the speedo. Tachos can be made to work easy enough.
Modern cars now though are moving away from all that stuff and going into making the gauges read directly from coded signals or pulses from the engine management computer. This makes it harder to use the gauges as they come out of the car, but with some clever modifications they could be modified to work.
A simple example for a custom setup would be to get some late rover gauges. The needles on these have internal rotation stops so that you can pull the needle off and change its zero position or even change the needle altogether without affecting the calibration. See example below:
So by using these internals, you could put them onto a single custom display board with numbers for tacho and speedo and put the fuel and temp gauges wherever you like, or replace them altogether with aftermarket ones.
I'm happy to take offers on the gauges shown in the pic. Ideal for a custom setup!
