What are you looking to achieve? If you are going to repaint with the same color as now, take the pump or an easier to carry piece to Sherwin Williams. They can color match paint for you. If the decal has the right color they can color match to that.
If you want a rustoration and not a restoration, clean up the pump with some Dawn and a microfiber towel, apply the decals and there you go!
Cool pump and a fun project what ever way you go
Dave