OK, I just checked SysSpeed, and the program has a
provision for measuring PPC clock. It reports mine
as 599 MHz. It also has some specific "benchmark"
tests for the PPC (so you can check your overclock
that way, too).
And I also forgot a few...the shell command "CPU"
gives the clockspeed, and also the benchmark program
"AmigaMark".
Anyways -- If you manage to clock up your Pegasos,
please let us know the details!