Early A body gas cap

you could always get a filler neck from a 67 and up,,and modify it to use the newer cap,,,but im not sure if the diameter is the same size from the older early A to the 67 and newer,,,any one have both caps to compare ??

i sold a N.O.S. replated early A cap to dave layson about 5 /6 years ago,,,had no idea he was repoping them,,,,nice that he is,,