Don't go for rotating LCD's.
First: the ones that are suitable for vertical mount (thus are non-TN) can be counted on one hand: HP LP2065, Samsung 214T, Dell Ultrasharp 2001FP, Eizo S2100 and the NEC 2190. These displays are so expensive, a 27 inch widescreen is cheaper and has about the same vertical size.
Second: Don't think there are other options. 17 and 19 inch is NOT 4:3, but 5:4, and most of them are TN, and TN mounted vertical absolutely sucks.
Third: The risk of having the mechanism turn out to be ugly non functional crap with stinking bezels.
Fourth: The risk you spend so much money on your stinking rotation mech, that you could have bought 2 screens and an extra set of control for vertical classics in the first place and use 1 for a dedicated vertical Mame machine.