Yeah, I think I’ve been using Mame 2016, I think it gives the vertical arcade image as vertical without any core rotation.
The main problem is that when ever the core is trying to do a rotation it rotates the whole viewport (even though you don’t see it, at first you only start to see it when you start drawing stuff in the viewport, this is what you are seeing when you see the distorted frame with extra thick frame on one side and thin side on the other)
Here’s some progress on the Black Cropping
Cropping Off
Cropping only black on