SS and XCVG: On my Retro64, I fried the first N64 which was an older one that supported RGB. I used the PTH08080 with a 2.2k resistor on it, giving about 3.1v. When I switched to the newer rev8 motherboard, it would no longer boot. I found a 1.8k resistor, giving it 3.3v and it all worked fine.
Contrary to what it would seem, the newer models have a lower tolerance to undervolting. If you want to be safe (and by safe I mean make sure it's getting the right voltage), then go with the 1.8k resistor, which will work with all N64's. Anything lower (meaning voltages above 3.35v) will probably fry your N64. You can't fry it by undervolting it, however, so there's no reason not to try. I can't find the thread right now, but Daftmike did some testing with an older revision and he got it to stay stable down to 3.065v or something like that. Lower voltages result in less heat. I'm not sure if it draws less current, though. It might.
In short, there's no harm in trying resistors higher than 2.2k, but 1.8k is guaranteed to work for all N64's. Just don't go under 1.8k.
