The Vive is backordered, but HTC seems to be keeping up with fulfillment much better than Oculus. If you order today, you'll almost definitely recieve it by the estimated date (which is about a month IIRC). Inversely, Oculus keeps pushing further back for some people, and new order estimates are for August.
A 760 seems risky. Basic stuff like a lot of the free indie tech demos people have been playing will likely be fine, but anything else is going to have issues hitting 90fps. My 970 can barely cope with Elite Dangerous, or even Rift launch titles like Lucky's Tale and Chronos. It works, but it isn't the flawless experience you want from VR. Even having a locked 90fps 99% of the time spent in game isn't good enough.