[40 Deluxe]

More to tuning a carb than swapping jets. At full throttle high RPM, air flow may be so great that enough more fuel is 'pulled' through the jets that the mixture may get too rich even though it is correct at lower RPM and throttle openings.
The fix is to enlarge the air bleeds so more air comes into the mixture and gives the needed high speed lean out. With a long duration cam you may need to drill holes in the primary throttle plates so you don't have to set the idle up so much that the transfer ports are uncovered. How big are the holes? Ah, that is part of the carb tuning procedure! Experiment until you get it right. Next, what is the best accelerator pump setting; #1 or #2 position? Which color cam? What size squirter nozzles? What's the best float setting-factory, or a little higher? Or a little lower? Have fun!