Stock carb settings are here. Std '18 is 128's.
4 1" holes in the airbox is a good idea.
Just bigger mains will be fine, Steve's the man to tell you how big, from memory not much different (if at all) from standard.
Lowering the front is another matter, you'll be able to do it by just dropping the fork legs through the yokes but you'd be better off raising the rear instead as the MC18 fairing hits the floor at serious lean angles anyway.
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