Trying it is the only way to find out in my opinion.
If you can stay objective, in control of yourself and not take nasty comments from pts. personal then you're a good candidate for psych nursing whether you have a psych history or not.
If a patient is "losing it" and about to code, you have to stay calm (at least on the outside) you don't want to get sucked into their world and be of no help to the other staff.
Where I worked there was only one nurse that I could say clearly had no business working psych. She was constantly flipping out, scattered brained, ocd, bizzare appearance and crazy fire red hair that looked like she just rolled out of bed

Whoever hired her should be smacked