Issue with mounting catalytic converter

Hey All,
Some jackass stole my catalytic converter and am mounting a new one. The issue I have is that one of the nuts on the exhaust manifold flange is rusted out to the point that the bolt to mount the cat won’t tighten down.. is there a fix for this that doesn’t require me to unmount the exhaust manifold?

 

Cut and or drill out the stud and replace it with a bolt & nut.

 

Get a hinged flange that can fit rite behind the rusted flange and use that to tighten down the joint.

Just had to do this on mine about a month ago.