rust in one of these old tanks is not uncommon, there are a number of ways to remedy that with out replacing the tank. it's such a common topic that you should do a search on this or another forum for details rather than me repeat it.
you will probably have to find exhaust specifically for a cb/cl/sl 200. either that or find after market pipes with the same diameter header.
most cb hand controls are going to be universal. though as i experienced just today the wiring colors may not match the scheme for your model making for some work deciphering whats what.
that said, many of the cb/cl/sl parts from most years are universal. but when you start talking about engine or carbs specifics you want to check for compatibility before you invest.
...connoisseur of slack...