Strat,
Classic parts of America (Chevy Duty) has this in a quart,part number 31-051. It supposed to be the light gray used in the cabs in those days. My ash tray was the correct color so I took it to Sherwin Williams and had it custom matched. I used their general oil based enamal that was about $25.00 I think. I sprayed the cab with a Preval system (glass jar attached to a disposable air sprayer.)I used black for my wheel and column and a no gloss black for the top of the dash and the steps. I know that its not the correct charcaol color but I dont care. I think Jim Carter has the correct color in a rattle can. I have been visiting different websites to try to find the correct colors for my 57 and it was a lot tougher than I imagined.