Can it be done. Yes.
Is it worth the time and effort and money to do it to a katana 600... Some might say that would be up to the owner. I'd say that's sugar coating it a tad. I'll go ahead and be blunt. FUCK NO.
Get you're carbs sorted or pay a carb guy to do it. Save up some cash and sell the bike for a better/bigger one. Or a smaller one if more fuel economy is what you're really after.
For all the time and work you're gonna have into it. I'd still be super impressed if the bike topped 100 horsepower. Might as well just be a different bike.