M3 rotors are 315 x 28mm. 330 are 325 x28. Thickness no probs at all, diameter will be unless you space them out. Just get on line and buy the brake motive M3 rotors on ebay. I have flogged them on the track and they are very good and very cheeeeep.
I have a 130,000 km 318is motor, M44 I think. Runs very well. Still in car. You can test drive if you want. In west Auckland but could transport elsewhere soon if you like. Pm for phone number if interested. Cheers