The ONLY reason to use any type of overclocking, given the risk of a warranty void, would be if your Mac is old and absolutely needs to be faster.
However, this rearrangement configuration lacks the necessity for any physical methods on your computer, except typing in everything correctly and understanding the directions. Once it becomes necessary to overclock the PowerMac you increase the chances of burning up something inside. You better keep that thing in a cool area and where there is significant air flow if you are going to maximize the life of your redlined Mac.
To directly answer your question, spring, don't do it. Unless you follow the restrictions I previously stated, you are likely to overheat something inside the PowerMac, thus rendering it as Apple's first DDR paperweight. 🙂
Regardless of what would be "nice", I'd like to increase my xBox PIII chip speed to 1GHz if I could have someone do it for me, but then I would have a greater chance of destroying the system/processor, which originally cost $300. Think about what would happen if you destroyed a $1000+ computer. 🙁