MattV,
When I was younger I put some 16" Chevrolet Z71 wheels (and very low-profile tires) on my lowered Nissan Hardbody truck. Well, they didn't exactly fit correctly, I took them to a machine shop and they "bored" out the center hole so they would fit properly.
I'm not sure if what your talking about is the same issue or not, but machine shops do just that, machine work, and they can do it pretty accurately too. Might be worth a phone call to check a price. I only had to do the fronts for my Nissan, but that was about 10 years ago, I don't remember what it cost me...