Well, I finally came up with a solution that works!
I took the day off work today and headed out in search of a friendly muffler shop. The first one refused to help me, said they couldn't work on bikes. The second one said they'd take a look at it if I brought the bike to them, but they couldn't promise anything. The third one tried to be helpful, but they only spoke spanish and didn't understand what I wanted even though I showed them a picture of the header pipe and brought both mufflers into the shop to show them. I walked out with this, free of charge:
The last place I stopped, I had better luck. They understood the problem, and charged me $5 for this:
He left the ends long so I could cut them however I wanted. But there's still one problem with this - Even if I cut it as short as possible, the mounting rail doesn't come close to the bracket. See here:
So, how did finally solve the problem, you ask?
I gave up, called Dennis Kirk, and ordered the Jardine slip-on. They're shipping it out this afternoon and it will be on my doorstep when I get home from work Thursday night. I'll have it installed before I go to bed, and I'll be riding the bike to work on Friday if the weather holds up.
Thanks to everyone who provided help and advice, but it just wasn't meant to be.
Joe