There were no 5.7 manual Camaros produced from the factory.

If you have an optical VSS or rather a signal that is the same as an optical VSS(which it should be), then leave it unchecked. The VSS signal in your case should come from a DRAC/VSSB as a single wire (brown IIRC), which would have the same signla s an optical, which IIRC is 5V TTL.

I'd grab another XDF and see if the Rev limiter selection reacts the same. Sometimes XDFs are not set up in a way that is intuitive, or sometimes not correctly.