I can swap the heatsink from another 604 and add a low profile fan to it if need be.

I know about OS 9 not being gully MP aware, and it doesn't bother me one bit. Having 2 CPU's in the machine just satisfies some inner geek lust for me. I've always loved the 604 chip and thought it had a real good future in store for it. It's 64-bit chip, PPC architecture and runs great! What's not to love?