Well, if all checks out as being "legit" with that watch (I'm no expert on those old Patek models, but it does look OK to me from your pics), you do have something quite high quality for it's era, and a very "collectible" name.
You may not know, but Patek Philippe is considered by many watch collectors/wearers to be among the "top 3" (or similar rankings from other people) watchmaking companies and has a very high reputation. So, considering that, you could expect - if all is "legit" with that watch, a quite high valuation (into four figures in US$ terms).
I'd suggest you look online for "comparables" among Patek collector sites. I know the current Patek website has an owners forum @http://www.patek.com/owners
You'll have to register with them (create an ID) and then you should be able to log-in and perhaps get some answers to your questions about the piece you have. You may be able to get a sense of value of your piece from the folks there.
You can also get a rough idea of market-value by searching auction sites like eBay for models similar to yours.