The behavior that I'm trying to change is a loss of power when the engine speed tries to go above ~4500 rpm with the throttle wide open. As I understand it, there are four parts of the CV (constant velocity) carburetor that are used to adjust the air/fuel ratio. The idle air screw, the pilot jet, the needle and the main jet. Each of these are used under different conditions and there is overlap with each other. The main jet controls fuel delivery when the throttle is in the upper third of it's range. It's "neighbor" which influences fuel delivery at mid throttle is the needle controlled by the slide.
I'll see how it works tomorrow. Last spring when I made the plastic air box I just didn't have the time to tinker with the jetting to try and get it running well.
Wednesday Update - Success! Last night, I installed the 135 main jets and the rig runs great. No hesitation or flat spots evident on this mornings ride into town. Granted, I haven't tackled any long hills but it definitely runs better than it did last spring when I first tried the airbox. I never tried this large of a jet last time as others posts on Soviet Steeds were suggesting smaller jets. Though if you have a freer flowing air box it makes sense to install a larger jet to compensate.