If I am not mistaken you should have received optional #120 main jets with your stage 1 Ivan kit for the option to air box modify which is what are essentially doing. In my opinion the hardest part of the job is having to temporarily hook up the vacuum lines to each carb for synchronization using a carb tuner. I finally hooked up permanent vacuum lines that are capped off for easy access to my carb tuner. Now it’s a snap to tune the carbs, essential because if they are not tuned the cylinders fight one another creating additional heat and power loss.