I think we have some other power supply threads in the various forums that cover a good bit of these topics, especially in the Hacks & Development section for building replacement devices. Good to see more progress though.
Essentially the following should interchange either directly or with minimum effort:
*Mac 128k/512k/Plus
*Mac SE/SE/30
*Classic/Classic II
*LC 500 series up to LC575 and derivatives (though similar I don't think the 58x models interchange)
*LC/LCII/LCIII/LCIII+/LC475 and derivative models
*IIcx/IIci/IIvx/IIvi/P600/Q700/Q650/PM7100 (though the later models have higher wattage ratings they're downward-compatible with the older models)
*6-slot Mac IIs (same deal-later models may have higher wattage ratings but they're downward-compatible)
*Q800/Q840av/PM8100
*Q610/Q660av/PM6100/various Performas (later models may have higher wattage ratings)
*Q630/PM6200/6300 and derivatives up to but not including the Performa 6360 or other PCI-based models
*PMG3MT/B&W G3/Yikes! G4/AGP G4 all use basically standard ATX power supplies
*GE/DA/QS G4s all use the same special ADC ATX-style power supply though it's trivial to mod these to accept standard ATX if you're not using ADC.
There are others that should interchange (several of the PCI Power Macs such as the 8500 and 9500 for example) but I can't say for sure since they seemed to like changing the harnesses around between models in this era.