The only starting points I've seen published are here. http://www.demoncarbs.com/Tech/DemonSelectionGuide.asp
(You're basically already there, so just for future reference.)
Then tweak to what your combo wants.
Crackedback and Hysteric have provided good info. I'd hold off on advancing the total timing until you've made a pass or two. Then if no knock and plugs look OK, bump it up.
Not getting full throttle? Now that is an all too common, even from shops. Get someone to help you or a big rock to hold the pedal down...
