I was able to get the 3500+ stable at 2.37GHz on a 215MHz system bus in the steamy confines of the Benchmarking Sweatshop. Unfortunately, I had to increase the motherboard's memory command rate from 1T to 2T to get the system stable at that speed, but that's not the processor's fault. With a 1T command rate, the highest I was able to overclock the 3500+ was 2.31GHz. That's a repsectable boost, especially considering that I only had to raise the processor's core voltage to 1.6V.
Because raising the system's command rate to 2T results in lower performance, I've left the 2.37GHz scores out of the graphs below. Frame rates at 2.37GHZ and 2T were lower than 2.31GHz and 1T, anyway.
A 130MHz clock speed boost is good for a few extra frames per second in Unreal Tournament 2003, but it's not enough to catch chips clocked at 2.4GHz. As is always the case with overclocking, your mileage may vary. Overclocking success is never guaranteed and can often depend as much on individual system components as pure luck.