The game I'm playing is Valkyrie no Densetsu (via Namco Museum Vol. 5)
The game is displayed like this by default:
As you can see, it's not full screen. When I switch to TATE mode on the game's options, it becomes full screen, but the game is rotated 90 degrees to the left, like this:
Is there not a way to rotate the emulator 90 degrees to the right back to make it vertical?