Yeah, the Chicago location makes that an earlier Flottorp, I believe. At one time in the past I had contact with one of Ole Flottorp's great grand children who was interested in getting an early prop like that, but even though I still have the contact information from then, it's no longer valid. Too, bad because that's where props like this belong, in my opinion.
I might be interested in buying it, but to be fair, your best bet is to put it on eBay and let me bid along with everyone else. You might find two people who really want it and if they start bidding against each other you'll end up as well as you can expect any other way.
If you do that it's important to list it as "early wooden propeller" and in the description be sure to include OX5 sized hub, "original condition", and mention the original Chicago location decals. Post here as well if you do list it.
You might also be interested in
this link, which describes Ole Flottorp's propeller factory in Chicago as early as 1915, although I don't think your prop is nearly that old. It would be interesting to know when the factory moved to Grand Rapids as that at least would establish a minimum age for your prop. I do know that much of the Flottorp history was apparently destroyed in a fire some time ago.