So you sprayed more matte paint on?
And as for the fuel gauge, if you have a new cluster and pump, your gonna have to start tracing wires. Look for frayed/broken, etc. wires and trace the loom back to the pump. I don't have any diagrams but it would help to find some for the wiring. Once you find the wire/wires for the sender, do a continuity test on the wire/wires between the pump and cluster. This will tell you if the problem is in the wire harness.