I have mixed feelings about this approach. On one hand I think it makes sense, especially if you are using a non-CRT monitor, as the info is presented according to what you see.
BUT, MAME has all the info you need presented clearly and correctly. The resolution is indeed for a horizontal monitor that only happens to be installed vertically and that's pretty clear when you see the 270 in there. If I had to vote, I would keep it exactly like MAME has it, because it's representing the hardware correctly and that's what MAME is all about.