The throttle response will definitely be better with a smaller venturi...
I think though that a .030" increase won't hurt that (not much anyway? ) and the top end will be stronger. (.220 is pretty small )
You could however "bell mouth" the openings in the carb barrel...and leave the central portion the stock dia. That will also give you a true "Venturi" instead of a straight through barrel opening, and the fuel draw might actually be improved, as well as the top end.
I agree Jeff...the area above and below the carb barrel can be re-worked and you can see an improvment.

IMO, with airplane engines, the top r.p.m. is generally not high enough to warrant/need extensive sleeve mods like we see being done to some of the car sleeves and cranks. Just a mild clean-up will suffice.

As mentioned previously...when it comes to material removal, it's better to go at it conservatively...at least at first.