Look on your trim tag on the driver's side of the cowl. If your car has factory paint & you see something like "xxV (or xxC) 54L 54U", then your guess of #54 Light Yellow is correct. The first 2 numbers & letter indicate interior color & material. "V" is for vinyl, "C" is for cloth. The second 2 numbers followed "L"are the lower body color. The third pair of numbers with "U" are the lower body color. If the "L" & "U" numbers are different, it was a factory two tone paint job. If both lower & upper numbers are the same, it was a factory single color car.
Tommy