The face background is a dark graphite colour, while the lettering is either white or white-outlined red, depending on the gauge.
There are usually any number of New Old Stock gauges, even Speedometers, available on E-bay, it's just a matter of biding your time until the right item at the right price turns up.
https://www.ebay.com/itm/NOS-Ford-11...1aGxg2&vxp=mtr
https://www.ebay.com/itm/1941-1942-F...JZWms8&vxp=mtr
https://www.ebay.com/itm/NOS-FUEL-GA...VXkSXP&vxp=mtr
If you have good working gauges with poor condition faces, there are also vendors that sell printed vinyl decals to apply.