You want an OS disc but you want to throw it far? That's kind of a contradiction. OS is for lines that can't turnover (i.e. hole has OB right), headwinds, ranging (i.e. precise landings, not gliding wildly around), OH, some rollers, exaggerated flex lines, etc. They're not really made for distance but for getting to the ground quickly and predictably.Right now I'm weighing between Teebird, Stag, and Vibram Arch. I throw LHBH and I'm lucky to get 300' out of my throws if I'm being honest. I have some OS discs but they are faster speeds and I can't throw them very far. I'm open to what ever brands..
If your Valk and Orc are hard faders for you, you definitely don't need anything as fast as a Stag (although the stability would be decent for your arm). The Arch is OOP like others said. The Teebird is about as fast a driver as you should be throwing much but it isn't really a terribly OS disc. With some form work you could outgrow the TB as your OS driver pretty quick. The DX Teebird is a classic and will bomb (same for the Eagle-X). I'd get either one of those or a light Star Teebird/Eagle but there are a lot of good drivers in this ballpark now.
If you really want an OS that's properly OS for learning all those shots I listed above, I'd go Banshee (the domey ones suck but for you probably still fine), Resistor (like a Banshee but flatter and zippier), Trident (limited production), XXX (very OS, especially flat ones), and maybe the Spark or F1 (no experience). The older but still goody classics like Viper (wider diameter like a mid) or Whippet are great too (MOAB is a Viper variant, very OS). The Bard and Harp are probably as much beef as you need for the most part but even a slow driver does fight the wind better than a slower disc will.