Guys - the picture I posted is my OS .40 on the profile.
BUT, I've run the SAITO .30 on a number of profiles and 1/4 inch clearance should be plenty for breathing.
I usually drill a 1/4" hole through the fuselage such that I can prime the carb from the inboard side.
On the larger engines, you can usually put your smallest finger over the venturi and choke it.
Bob Z.