Welcome. First order of business is to NOT buy and use aftermarket rebuild kits. Stick with the stock brass. Gaskets and O-rings can be replaced as needed, but just about anything else is better stock and reusable.
Rough running is likely attributed to carbs needing a full clean. There's small pilot circuits that need to be cleared, fuel lines and tank filters that must be clean, and a good, full tune up. The hanging idle is likely down to a vacuum leak either in the rubber carb boots (between manifolds and/or air box). With the bike idling, spray some aerosol around the carbs, the manifolds, boot clamps etc and listen for an RPM change. This usually helps you pinpoint the source of the air leaks.
You can pull down a factory manual off this site to help guide you thru performing the renowned 3k Mile Service interval.
