Personally don't see much of the point to using car speakers for arcade cabs when there are plenty of shielded pc speakers. Using pc speakers also simplifies setup and saves buying and mounting a separate amp.
But that being said, you should be fine with most cabinet dimensions because the speaker shelf is usually far enough away from the monitor. It's also best practice to keep the audio lines a little bit away from the monitor.
If on the slight chance, you do get discoloration due to your speaker magnets being too close to the monitor, then Bucking Magnets on the speakers may very well help. Look them up.