" If it needs restriction in order to run rich enough, then it simply needs a leaner (smaller) jet and NO restriction."
CORRECTION... It is still too early in the morning ;-)
I should have said if it needs restriction in the input side of the carb then it simply needs a LARGER jet (to compensate for the choking affect of the restriction) and then no restriction.
You want to give the carb all the air that it can possibly use, then jet it to accordingly. You don't want to regulate your fuel mixture by choking the input side of the carburetor for two reasons. One, it will give you less fuel/air mixture (read less available power) and two, it is ver irregular, i.e. mostly affecting the wide open throttle and not at all affecting the low throttle.