why remove airbox? To pull carbs? no need. Just pull airbox+carbs back 1/4" and remove left rubber manifold between carb & head. This gives enough room to pull carbs out left side.
I do this twice a day at track since optimum afternoon jetting requires going down one size main-jets compared to morning mixtures. Then I repeat on Sunday.
Tank looks like prime candidate for electrolysis...
https://www.team-bhp.com/forum/motor...-proofing.html