So that would be a "PowerLogix Blue Chip G3 500" or a "Sonnet Crescendo/WS G3 500"?
One nice thing about the WS's & choosing CPU upgrades is that you don't have to choose between fast G3 and not-as-fast G4. The G3 & G4 upgrades both top at 500MHz, making the G4, if available, the easy winner. btw - If you come across a G4 WS upgrade.. Let me know!!!
As for the RAM issue:
The bus runs at 83 or 66. Even the 66MHz ones came with (I think) PC100 RAM. The bus can only be cranked so high by an accelerator before things go awry. Either way, I'd guess at best it is 100 Bus at 5x Multiplier. PC 100 would work. Go with 133, and you can be sure your bases are covered. As for the type, I'm not sure. I've heard the term "Low-Density", but idk exactly what that means. (I believe it is a greater # of smaller chips, but I'm not sure. :?: ) I'm glad you posted this as I still need to max my WS's RAM, and the input will be helpful.
EDIT- Forgot, Allegro also had their "Super Cool" G3 500.