Well, I'm heading out to Junior Gold tomorrow and I am in a tough spot, I can only bring seven balls due to travel limitations, and I'm coming to you all for advice. My stats are 350 RPM, at 17.5 Mph off my hand. My options are Roto Grip Idol, Storm Phaze II, Storm Son!Q, Storm Hy-Road, Storm Pitch Black, Roto Grip Hustle INK, Storm Ride, and Storm X-Factor Triple XXXTreme.
And if you guys had any tips, that would be greatly appreciated.

I would take all except the XXXTreme.

That's a pretty nice bag for a junior bowler.  Hard to go wrong with any 7 of those.  I wouldn't sweat it too much and go with what you are most comfortable with as Doom says.

I just looked up the equipment rules and Junior Gold only allows 5 balls to be checked in and no substitutions. No sense in taking an extra 2 bowling balls if you don't have to.

5 ball rule doesn't go into effect until after the practice sessions being held today and tomorrow at all of the centers.