Update, Chun-Nan's AppleSMBIOSEFI.kext did the trick when i dumped it in S/L/E. No idea why I didn't try that before, probably used to using an "Extra" folder

I know Andy's AppleSMBIOS was loaded correctly when I gave it a whirl. Actually, it did sort of work, as it did correct my CPU speed in System Profiler, it just didn't fix the "About This Mac" crash.

I'm happy for now, but I would like a 64bit solution so I'm future proofed.