FC304,
HQ and Commodore are different. Whilst you can interchange them and get away with it, it puts a hell of a load on the wheel studs. There is a real risk of snapping wheel studs under load...
I'd strongly reccomend not to interchange the two. If you want to use HQ rims, have the rotors offset drilled and use oversized studs.
Wheel choice with Commodore stud pattern is often limited by fouling (tie-rod ends, grease nipples or inner guards) - I assume here that you are running a HR front end. Be aware that Commodore offset varies significantly - 26 to 43mm is common.
This thread gives some info on offsets:
http://www.fbekholden.com/forum/viewtopic.php?f=27&t=2849, whilst this thread gives some info on legality (NSW RTA regs):
http://www.fbekholden.com/forum/viewtopic.php?f=27&t=14204Cheers,
Harv.