Although 3/4 is
ideal, as the above 2 posters have said (Steven even prefers 3/4 for Amazons) and I agree... I know a Jardine's head not even including the eyeballs sticking out at the sides is well over an inch wide. Gently put her head up to the bars so you can see for yourself how it measures up. That is what is ultimately going to make you most comfortable with the decision. Actually seeing Jardy's head in relation to the bars.
I think that purely based on looks though, the larger cages with 1" spacing "look" better with a larger bird inside. But since you just got the cage already, safety wise, I'd
personally be okay with it for a normal sized Jardine's parrot. Those Pois have big heads

.