I was at a Ford resto shop cruising for the FORD Letters to replace the ones on a 66 Road Car. I looked at the Blue Ovals for me. There must be 14 different versions(sizes) to choose from. They must have made them a different size for every model. So you just have to choose the one that you think looks best. Also, if you use an old one, the color varies, probably from fading over the years.
Bill