If that doesn't work, measure the outlet size to see if it is really closer to 2 1/4". There may well be some aftermarket choices there as most headers use that size on the back end. How I fitted up my CB550F, the muffler itself was dead but the pipe size was right to pop on a Vance & Hines rear muffler section off a bike with a trashed front pipe section. Went on like it was made for it and looks great.
You can go to the Dennis Kirk website to check out the rear pipe offerings they have there. SuperTrap is one that comes to mind.