hi vc to vl commodore discs will bolt strait onto an ra40 celica without any mods whatsoever. you only have to make new backing plates to hold what ever calipers you want.
i used volvo 4 spots arount $200 for a good set. this also gives you the ability to run commodore mags which sounds like a strange thing to do but just about every mag available in australia will be available for commodores. the commodore disc gives you the right off set as well, with out any spacers.