I would avoid the jet kits and just buy a range of oem jets. Get a cpl smaller and a cpl bigger than what you figure you'll need, then you can do a proper plug chop.
Proper plug chop ? I have a 270 main jet now and my mods are stock bore as far as I know ... And fmf fatty with fmf power core silencer no air box lid with moose racing filter and soon to be adding after market reed valves