@Jose
I was able to run mine (F43G) stably at 66MHz, although any more
(even a few MHz) would start crashing the FPU.
BTW -- Mine was rated at 60MHz, but there are quite a few running
their 50MHz "F43G"s at 66MHz...most should handle it reliably with
some cooling.
The ultimate would be one of the newer 060's...some of them can
be pushed up to 100MHz. One of these on an AGA amiga would make
a pretty cool machine for watching old demos.