There were a bunch of of 500MHz rated 7410's clocked up to 600MHz and sold by FastMac and OWC. I had one in my G4 Yikes -- ran it at 650MHz.
700MHz ran too, but turned out not to be stable over extended periods. I think I'm the only one to run @ 700MHz in that machine while keeping a 100MHz system bus.
The 7455B was very good for overclocking. The highest it came rated was at 1.25GHz but it was sold "guaranteed" at 1.467Ghz and 1.5GHz speeds by various places, including OWC and GigaDesigns.
I had a 1.2GHz rated GigaDesigns 7455A "guaranteed" at 1.33GHz which it ran beautifully at. I tried it at 1.4GHz and 1.46GHz but it would not boot, not even with a voltage boost.