That's what i did also...drilled out the old rivits, and reattached everhthing with grade 8 hardware.
I used the rubber piece from one of the universal hanger kits at Pep Boys, but you can also get even better pieces from any muffler shop.
Just take the hanger to the muffler shop with the right length in mind and have them sut you a sturdy pices form their stock. They might charge you $5.