If you have only 330s on the front with four pots, then the 315x28s required to fit the four pots on the back would be HUGE over-kill and require a bias valve to reduce the breaking to the rear (especially if it is a 2wd car).

The 300mm discs using a 4x4 calliper will be more than up to the job. This is what they would look like on the car .