If its a wideband a/f gauge i would get something like oil temp or egt. Or if you want to put one of those in the cluster and put boost in the piller. If its a narrow band light show gauge ditch it and get a real wide band with wide band o2 sensor.
Personally i will be putting new oil press, water temp, and boost in the stock locations with more accurate gauges and then have oil temp and egt in the piller as my wideband is on the steering column cover.