Seem to be several ways to approach the issue. Pick and choose what you like:
1. If you actually want to revert to E975, flash a stock KDZ.
2. Flash another customized ROM that is designed for E975.
3. Edit "ro.build.product" and/or "ro.product.device" in build.prop to make you phone identify itself as E975 (that's where the F180 comes from, so change it).
4. For any ROM that refuses to install, edit an install script to modify or remove the assert line that validates the phone's model.
IMO, #3 is the proper way to fix your issue long-term, and #4 is a backup option when some zip still refuses to install, and you just want a quick fix. For example, this is how I install PhilZ Touch CWM that is packaged for E975 (I have an F180). But keep in mind that you are bypassing a failsafe measure, so, if you screw up your phone, blame yourself.