It should, yes, but it won't work. The 6500 requires 3.3 volts, but the Performa case and power supply doesn't provide that. If you wanted to do something like that, you could make a 3.3 volt regulator and attach it to the 6500 motherboard like so:
http://www.mac68k.org/~john/fifi/
My motherboard isn't a 6500, but it's close. My guess is that it's from some sort of 6360. I found the motherboard in the trash in NYC many years ago and transplanted it into a Quadra 630 case.