The condition hurts the value but I like the fact that its a 6 1/2 ounce instead of the usual 7 ounce. It looks dug and might increase in value after its been cleaned. What's embossed on the base in the way of a makers mark and date?
But with that Owens-Illinois mystery plant #24 that I've seen before and believe was located in California, but can't recall if it was in the Los Angeles or San Francisco area. Notice that none of the attached charts list plant #24 ...
I'm going to double check my files and/or look around and see what I can find. I know I have encountered that plant location before but just can't recall where it was at the moment.
The one thing we didn't address is your question about the bottle's value. The poor condition of the label really hurts it. The main thing it has going for it is that its a 6 1/2 Ounce. That's pretty unusual because about 99% of the early 7up bottles are 7 Ounce. A collector who doesn't have a 6 1/2 Ounce and just has to have one is probably your best bet. I'm thinking if it cleans up without causing anymore damage to the label, and the fact its a 6 1/2 Ounce, that you might get about $10 for it. Otherwise it doesn't have much value. Collectors are pretty particular these days and unless a bottle is extremely rare they usually want them in near-mint condition. If your bottle was in near-mint condition I'd offer you $25 for it, and I feel that's being generous.
You initially said "found this the other day." Does that mean you found it in a dump or in an antique shop? If in a dump, I'd go back and look for more. If you find another one just like it that's in near-mint condition, then you'd really have something.