It will clear fine with 17" depending what wheels. I'm running 17" and my setup is larger than 323mm
It's not the disc size that's the issue, it's the width of the caliper. It depends on the offset and width of the wheels, you'll struggle under most 17's without spacers.
I think I remember seeing a build thread on ED38 with them squeezed under 17s as a temporary fix but they needed shaving slightly and even then there can't have been more than a hairs width.
I have also read that thread, they did have to grind some of the caliper away.