Hi everyone. got some free time this week, so I tested maverick on my computer.
i7 3770k ivy bridge (hd4000)
Intel 335 SSD
ATI 6950 (flashed to 6970)
finally I was able to make everything working.
1st. remove the ATI Video card
2nd. Create a USB Mavericks bootable key (many DIY on this)..
3rd. download FBrotate from Apple Store
4th. on prefs, users, add FBrotate at the startup (it will resolve the blank screen from the 6950/6970 bug)
5th. install latest chameleon, edit org.chameleon.boot.plist
6th. reinstall the video card, boot your favorite OS, you should see the 6950 correctly on the system information (if it's ok, you will see Graphisme AMD Radeon HD 6950 2048 Mo, if not you should see 6xxx)
congrats, you have a working ATI 69xx mavericks setup, no integrated video / switch things to do...