I think you might have some Keihin FCR carbs on the bike?
They are a HUGE improvement over the stock POS Mikuni BST Vacuum operated carbs.
The stock carbs are just junk.
Those Keihin Flat slides are pretty costly too, I think you got lucky.
The airbox is so frustrating to remove and replace, it makes people like me want to go Postal, so we remove it and go with pod filters on each carb.
Pods are real easy to work with...
If your bike has the Flat slides, with velocity stacks and no air filters, you can buy adapters from
Sudco International to fit the air filters or even the stock airbox if you want.
You'll have to have the bike re-tuned if you make a change.
The pieces of body work your missing mount between the fuel tank and the side panels?
They're Stainless Steel and rivet onto the plastic side panels and should be easily remounted.
I've considered removing those pieces on the side panels on my bike, to make it easier to get to the carbs, but figured it was a little extreme and would let rain water get into my pod air filters.
When I'm tuning my bike, I just leave the rear body work off durring test rides to make it easier on myself.
Here is a couple comparo pics, so you can see the difference between the looks of the Keihin FlatCR's and the MikuniBST CV carbs.
This is the left side if the KeihinFCR, notice how they sort of slope back away from the Top end of the motor.
This is the right side of the MikuniBST's... Notice that they have black plastic tops on them that are destinctive.
Check out the body work on my bike.