Dave, this is a belated thankyou for posting your last to point out you did think the bored out carbs did make a difference. It appears though that you may be the only guy we know who's had it done. Lucky you hey?
All those little things put together would add up I'd imagine. Here in Aus I've probably got Buckley's chance of finding someone but maybe Thunderbike across the ditch may have the expertise.
