I believe the 700s are now harder to find.. and if they do, probably the dud ones left but if you can manage to find the one with cC0 or cD0 stepping, you should be able to do 933 or upto 1050+.
The 800s are not very good at high overclock. You would have to make sure that you get the latest stepping possible. Get the 800cC0 or cD0 rather than 850. Lesser the multiplier, the better chance you might be able to OC higher.