I was able to find the wheels again:
http://www.summitracing.com/parts/mbw-61324/overview/
I saw that someone on Moparts had basically bolted this wheel style right on to a '68 Satellite Wagon, and I've seen them on some other brand-x muscle cars so I think they may actually have a hub center that is the right size. If not, at least they have a bolt-on center cap so opening the inside may not effect anything at all. My car has the 11.75 stock rotors at this point - so based on what you said, it sounds like I may need somewhere around a 10mm spacer in the front. I have the Hotchkis UCAs on the car now.
I know it will probably perform better on a 10" wheel, but at the same time I'm not quite sure I can find wheels that look classic enough in that size and not pay a ton for them. If I actually get into doing SCCA CAM-T autocross I may get another set with some direzzas or something.