No actual RT experience but what I'd do (& you may have done this from your descrip) is measure across the carb air cleaner side to side & get a dimention of the carb height to the "grooves" on the fenders on the sides where the hood sets down into then get a measurement on the hood, the "height" of the bottom of the sides (which contact the aforementioned fender grooves) compared to the inside metal where the air cleaner would touch then compare that to your first fender dimention. That might get you pretty close. Other than that if no one replies I'd mockup and see what you get and a drop base air cleaner will help tho you need a certain amt of filtering element sq in of area and the top lid cannot be too close to the carb bowl vent (no specific numbers on either of those last two but the info is out there)