Gorgonops said:

You can change what it identifies as, but don't you have to swap a crystal too? (IE, I know if you fiddle with the ID bits you can make the board identify as anything from a Centris 650 to a Quadra 800, but the speed is still dictated by the oscillator.)

Click to expand...

Well, as I've mentioned before, my memory is old and crumbly.   Does the 25 => 33 upgrade require an oscillator swap?   Some of them just needed a resistor change on a clock generator, but the Centris/Quadra may still have been oscillator controlled.  

Okay, I went and looked at the mirror/preserve of Marc Schrier's Clock Chipping Home Page hosted at applefool, and it was indeed an oscillator swap.   Thank you.

So, an oscillator swap and a couple of resistors....