i'm doing the same on mine as well, and i'm using the thick ass polini gasket material for more RRRRREEVVS. I'm also thinking i might bend the keeper tabs back a couple MM to get it to open more.
they are two holes because the standard reed is 2 petal, less mass per petal and quicker throttle response... in theory. i've also ported the outside of the reed 'cage' cast into the head so i can go wider on the gasket.
i've got a 22 mm kehin knockoff or a 20 mm mikuni knockoff i'm trying to decide between. i'll get some pics up on saturday when i throw all this shit together. its going on an A3 so replacing all the bearings and doing all the work on the crankshaft has taken me a lot longer than expected.
what are you planning for pipe... did you see that 11.2 hp polini pipe the dutchies posted, i'm gonna be making a copy of that i think, maybe a few mods for alky (e85)