You all missed something very important. The instrument panels on KF cars have a voltage regulator on them. It has been proven that using a 12V charging system does not alter the gauge performance. Making the VR drop 14V to 5 instead of 7V to 5 does not appear to after the longevity of the VR. I have seen 2 KF panel VRs fail and they were running on 6V systems.
If you are using a different gas tank sending unit (don't see why you would need a different cooling temp or oil pressure sending unit), you need to match it with the resistance range of the original KF sending unit. The shop manual tells you what those values are.