Lots of guys run BMW pattern wheels on gm cars. Plenty of people say it's a bad idea but plenty say they do it with no issue. Here's a good thread about re-cutting the wheels to 5x4.75
http://www.thirdgen.org/techboard/wh...t-pattern.html
I have a set of Racing Hart wheels in the BMW pattern. I haven't put them on anything yet but if I'm not happy with how they fit then I'll do like in that thread.
As far as back spacing. You didn't say what car you have but I don't think 11" wide wheels fit on the back of too many muscle cars without mini tubbing.