Air gap versus MP M1?
If you do go M1 and run a square bore carb, get some Moroso epoxy and fill in the spread bore to make it a square bore carb flange.
I went M1 because I was not concerned low rpm performance. Doesn't hookup on the street anyways. Especially with my stiff handling suspension. In my particular situation, I was concerned with the car on the road course at 3000 to 6200 rpms.
Hopefully it shifted the HP/TQ curves upward? I dunno without a dyno.
I do have an Edelbrock RPM that I am holding onto to try some day.