Bus speed on replacement laptop CPU: how close a match?

[RoundsToZero]

I'm looking to replace the CPU on my 2004 ThinkPad T42 with something a little faster. Currently it's a Pentium M 735 which is 1.7 GHz with a 400 MHz bus speed. I've found similar processors with faster clock speeds but 533 MHz bus speeds. Specifically I'm looking at a Pentium M 760, which is 2.0 GHz. Will this work on my motherboard? Southbridge is ICH4-M. My guess is yes, since most of the Intel motherboards I see on Newegg are 400 MHz / 533 MHz. I'm thinking I probably have one of those, since there is no [slower than 400] MHz / 400 MHz option on Newegg.

I'm hoping to get some feedback from someone more experienced swapping CPUs. The only time I've moved a CPU between machines, I knew exactly what hardware I had, and had control over what the motherboard on the new machine would be, so I could just make it an exact match.

Sorry this isn't more Gentoo-specific but these forums are very helpful.