My G3 750FX is rated 800 and runs at 933 OK.
1Mhz is acheivable as well as its documented how to get this on the G3's.
Helgis has a G3 clocked to 933Mhz as well.
I suggest you ask your dealer about a cpu module upgrade. Or ask to be signed upto the dev-list, or the Amiga one owner forum at AW.net.
Lots of discussion going on about the newer G4 modules there.