Surely you want the settings to match the source material?

But which one?

From what I can tell the bitrate doesn't matter. It will still be lossless. The only thing that changes with a lower bitrate is the time it takes to encode.

Your sauce file isn't working. But you want to have the same sample rate at the original material. No point going higher.

Yep, the thing now is to find where I find the place that that info can be found.