@Polyfusion if you are using the latest version of EmulationStation (you would need to use the emulationstation-dev module in RetroPie-Setup to install the latest code), there are a few new options available that should work for you. They are command line options so you will need to modify the startup script to add them.
The options are
Assumming your LCD is 1080p, I think you would want it to be sometime like the following, not sure what the screen offset values should be though, you would need to test out different values to see what works best.
emulationstation --screensize 1440 1080 --screenoffset ? ? --screenrotate 1