The gas, oil, and water gauges work by the sensor changing the resistance to ground. I'm thinking adding another item to that circuit would not be good. Also, the older Mustang (and others) gauges work on a 5 volt system and I doubt that newer equipment is compatible.
1968, hardtop, 289, C4, seafoam green.
1966, hardtop, 289, original 3 speed, on the road and fun to drive.
1968, hardtop, 200, 3 speed, new project car, Nov 2015