I do not have a "jr." But, I have a super victor and with the right air cleaner I "think" it would fit? Not sure on the "jr."
it will fit but only with a 1 to 1-1/2 inch drop base air cleaner and if you do that i'd advise that you cut the air horn off the carb so it can get some air. but i'd just go with a RPM airgap and for get the Victor Jr... unless you have some unrulely cam shaft and some way ported heads