Paul, I bored the spacer and the manifold together so they match, no step at all. So like you said no radius is needed.
Carb is rebuilt and manifold is on!
The throttle linkage shaft on the 38 is shorter than the 32-36 something wrong here!? Working on that next.
Here is a picture of the manifold with spacer and insert.
Hopefully it will run!
Lyle