Man, I'm sorry, but I'm afraid you'll get a lot of opinions that it's only worth what YOU will pay for it, and how bad you want it.
I'm no expert, and that looks to be a WWI vintage Colt with original parts, but it's been so heavily polished and plated that any collectible value has been ruined. The United States Property rollmark is gone, and even the Colt Pony has been polished off. And that engraved name REALLY kills it.
It's only worth what you're willing to pay, and try to turn into a decent shooter. Ain't no collectable anymore. I'm thinking $600 is way too high. You can find a lot of excellent brand-new 1911's in that price range.
It COULD be de-plated, refinished and refitted, and made into a nice looking, nice shooting new best friend, but that's a lot of work and money. I wouldn't pay 600 clams for a project gun.
But that's just my opinion, and worth what you paid.