well supplying power to it, your fine. i think the on board regulator can handle up to 12v.  im not too sure about the 8MHz crystal though, i dont think theres any conflict with that.. but im not sure. the optocoupler is powerd by pin 4 i believe. and the LED's... what i suggest you do is put the blink code on there, but make the durration pretty long to test it. get a multimeter and see how many volts pop out of pin 13. then, use this http://led.linear1.org/1led.wiz to figure out resistance. might want to do that to pin 4 also. hope i helped..

I'm about to start building an arduinoboy, and I was wondering if anyone has ever built one with something other than the nano or the uno?

I was wondering if specifically the Fio was a possibility?

The issue I see with it is that it only has a 3.3 volt output, which I didn't know if that would make it usable even if the resistors were changed?

Thanks for any insight you can provide