High Sierra successfully installed in my L321X i7-2637M!!!
What works:
Webcam
WiFi (switched with DW1510)
Audio (internal speaker / headphone)
Keyboard backlit (Fn+F6)
Brightness slider (remap F4/F5 with Brightness Slider.app)
Sleep / Wake (with LID close / open)
Mini Displayport Video
HD3000 graphics
Thanks a lot.
EFI L321X High Sierra.zip