@jgeibel @wossquee Not sure if you still care about this, but this is now possible by using the new retroarch core dosbox-pure. Just tested it out and now I'm able to get this pinball game working vertically on my cocktail table setup. Now to add 2 flipper buttons on the side so it plays like a real pinball table.
Also note that I had to change the IRQ setting to use IRQ 5 instead of IRQ 7 (the default) to get the sound effects to work.