Sorry man, these aren't going to be worth investing in. I collect a little bit of signage myself. The only Coca-Cola one I have a 36" porcelain Coca-Cola button from 1954ish, but porcelain is a LOT different from pressed, painted, steel signs.
The difference between the sign I have and the one you are referring to is not only the material, but people back in 1954 didn't think keeping an old sign would be worth the space, so they just threw them out. Today people will grab any sign they can and hoard it or hang it hoping it'll go up in value, plus Coca-Cola collecting went through the roof about 10 years ago, and it hasn't really diminished
Here is the one I have, kinda hard to tell it's 3 feet tall in this pic