Hi Scott.
Firstly:
Yep, got the noise sorted but can't honestly say which bit was the culprit. Once I tidied up the wiring and mounted everything properly it quietened down a lot. Theres still a bit of noise but no worse than any OD pedal I reckon.
Secondly:
9V will be fine but you'll end up with less HV (about 50V instead of 80V). It'll just fuzz-out a bit sooner for you. The only thing you'll have to alter is the heater wiring. Instead of going through the heaters in series (pins 4 & 5) you'll have to run them in parallel (pins 4 & 5 shorted together and out on pin 9). You'll also have to drop the 9 volts down to 6v by using a 6 volt regulator. You can buy an LM7806 and a couple of caps at Jaycar for about $3.00 I reckon. The heaters will draw about 300mA so you may need a small heat sink on the reg. I imagine you're OK with LM78XX series regulators so won't need a schematic. But if anyone else wants to do this please see the schematic below. It's a bit fuzzy because I took it without putting my glasses on. It's a bugger getting old!
Have fun.
http://www.pitbullguitars.com/wp-con...7v0b-image.jpg