Chris,pull it back to 10.5,we've had nothing but grief in recent times with comps any higher than this given the nanny goat piss(see petrol)available these days.The 98 available from BP will give you the right bang for your buck,and forget octane booster(long term)too costly and next to worthless unless your throwing litres at it at a time....Avgas...hard to get,expensive,not available by pump unless your very friendly with your local airport authority and furthermore we are being weened off it at motor sport events more and more as the years go by.In time it will be banned for motor sport.
KISS 10.5 will be more than enough but i would DEFINATLY put it on a chassis dyno.
Research an operator by phone(may take a while)and if he's any good he will give you a basic jet/choke set up over the phone prior to taking it to his dyno once you explain what the engine measurements and goodies are.