The SVRA groups can be confusing, the '72 rule is blurry. It all depends on the level of prep. We discussed it briefly here: http://www.classiczcars.com/forums/showthread.php?t=36348 In summary, technically any thing S30, up to '78, is legal for SVRA group 8, but again this is dependent on the level of prep. You could even run the stock fuel injection if you wanted to. I forget, but I beleive group 9 is actually for open wheel cars, or maybe Canam (their website is down at the moment) The other place you may see a Z is in 10 but these are typically the later GT2 style cars with flares/slicks and tube frames, partial or full.