Voz, to answer the question fuel gauge is 0 empty and 90 full if you plan on using the existing sending unit. The autometer is not plug and play. you will have to rig some mechanism to hold the gauges in place, and will not be able to use the printed circuit for signal and power with the new gauge. There is an aftermarket gauge cluster back plate (it fits into the dash like the stock plastic piece) that you can purchase, and then all you need to do is wire things up, but you will also have to make certain that the sending units are all matched to the gauges.
Here is the autometer gauge panel for YJs from JEGs