Yes it SHOULD see the iMac as a Windows 10 PC. However I'm not sure about the drivers for the Pro 580 in Bootcamp and whether you are getting the most out of it. Also I wouldn't say "certainly the specs are up to the job". They should be yes, but I've used VR on much more powerful hardware and found limiting settings required.
It will all depend on what you are doing. Porn (if thats your thing I'm not here to judge), movies, virtual tours, etc etc will all be fine. Certain games using a more powerful R9 Fury I've found stuttering and frame rate drops.