1976 Scamp fuel gauge problems

The car now has a working speedometer, temp gauge, and fuel gauge. The ammeter is burned up and none of the dash lights come on, but the three main gauges work along with the turn signal indicators and the oil light that's stuck on. Now the fuel gauge always reads just over empty and it should work properly once I have a new sending unit since it pegs when I short it to ground at the tank. And the worst part about buying a cluster and making one out of the two is that I stopped at a friends place, told him what I did, and then he goes and digs in his shed and pulls out a correct, potentially functional cluster for the car that he said I could have. He told me it's been sitting in there since the late 90's, so it may or may not work. Since mine does all that I care about, I don't know if I should try to mess with it much anymore.