Re: ViewPortIn and ViewPortOut in 302.07
We made a decision to remove the idea of "front" and "back" timings in favor of just driving the mode requested as the actual hardware mode and using the transform to specify scaling. This provides extra flexibility while also making it clearer what mode timings are actually going to the monitor. It also lets you specify whatever size you want as the ViewPortIn, rather than being limited to what's in the output's mode list.
Future releases should make this easier to configure via nvidia-settings, and I expect the various RandR-based open source tools to gain support for this too as RandR drivers start to have better support for transforms.