The way the bottom two points of the star go into the text, the way the red 'settles' in to the top of the 'X'. It's a cut down 42"
The sign in question only APPEARS to have a thicker black border than 42". If you look closely and zoom in, what appears to be a black border on most of the sign, is actually bare steel. The sign in question may have been cut down 1/8" into the red, as I see NO porcelain at all within an 1/8" of the edge. If you look closely the thickest portion of black border is in the lower left near the word 'MADE' and the black still doesn't go to the edge, it is chipped there as well (approx. 1/8" from the edge). All of the black on the right side of the sign is pretty much all bare steel. In-fact most of the border is bare steel (chipped porcelain).
Your sign would have also been cut from the example on the right in my photo, because it says "REG US PAT OFF". The one on the right is the older sign from (approx.) 1929-1935, which was usually single sided, which makes sense with the sign in question (This is not always the case though - there are DSP signs before 1935). After 1935 they generally used the double-sided "REG TM".
I don't know if any of that made sense, but it is definitely a cut down 42".
And to answer your question.... definitely not worth $1300.
My 2 cents,
Here are two of mine for reference....
Last edited by Speedracer; Sat Feb 23 2019 12:24 AM.