We have quite a few inliners from Wisconsin, surprisingly.

I'd look into Porter Mufflers. Kinda old school, and I personally enjoy the sound - might fit your project? They have a website, if you want to check it out.

-Sam.

1967 Chevy II, 2-door post.
250, 3-OTT.

1969 GMC 1/2-ton.
307, 3-OTT.
DD.