Hello there , I thought that maaybe I could help you with your thought about gauges, any gauge that you decide to install in your car or truck, can only benefict you in the long run.They inform you of the operation of your engine at all times, a drop in oil pressure would tell you basically to shut off your engine to avoided engine damage, or a amp guage would show you that you have a serious charging problem. Anyhow any guage that you install in your vehicile will only incearse your awareness of the operation of your engine plus the look really NICE.
One last thing I use all the most popular gauges , oil pressure, water temperature, volts, amps ,vacuum, and of course tachometer. And buy good quality gauges .IE auto meter(auto gauge.Have Fun.
You'll have to break down the harness into the individual sending units and run them accordingly to your aftermarket guages. Just go to where the various sending units are and trace the wires from them into your cab.