If you haven't bored the manifold to match the carb, that is a problem. The manifold as cast has only a 10mm bore and the throttle plate is 14mm. The manifold is designed to be bored out. The venturi is larger than the manifold bore. Just bore deep enough to remove the built-in restrictor and blend in to the main body. The manifold matches the intake port well.

Ralph;
I hope you can get one of these. I would like to see one with your ignition.