We've done this so many times I can almost do it off the top of my head.
It's an easy conversion but there are some complications with re-wiring the dash plug. You will also have to get a temperature sensor for the dash gauge because the idiot light sensor is different.
The charging gauge will have to have wires run to it and fuses put into the harness to protect it. It almost takes a complete thread just for that.
Here is the changes to the dash plug that need to be made.
This diagram shows the added wires for the battery charging gauge with the fuses. Your wiring should be the same except for these two small 20 gauge wires.
Here are the two ways the cluster plug is pinned so you will have yo remove the unused wires and move the others to match the gauge cluster. The blue wire at no.2 and the green wire at no. 5 will be removed and the gray wire for the dash lights and the pink wire for the fuel gauge need to be moved.