Kz550ltd airbox swap

So I’m rebuilding a KZ550 LTD (1981) and the guy I got it from had cut the airbox out so I replaced it with the pod filters. But theres that huge rubber tube left... what the f**k do i do with that?!

It is a little difficult to tell from the picture, but that may be the air line to the clean air system. Most folks remove all the hoses, then buy or make block off plates to go over the reed cages. Personally, I would be far more concerned about how butchered the frame is.
Have you checked the Articles section of this website for a downloadable factory service manual?

Additionally, there should be a crankcase breather tube that's normally routed to the airbox.
The frame needs some cross bracing welded-in at the least. can't tell what's been done to it.

www.partzilla.com/catalog/kawasaki/motor...-cleaner-80-81-c1-c2

ps: be careful w the gasoline in the garage, especially if there's a gas water heater or dryer.