Our team actually used a similar mechanism for Breakaway to kick the ball. Our biggest challenge was latching that much force in a spring. We ended up using 2x 2in dia, .5in throw cylinders to do it. That being said we were drunk with power with the fact that we could kick the whole field that we completely forgot to design a decent aiming mechanism.
Lesson for this year for us? Don't focus only on power.. Balance that with a good way of aiming.