If you mean by piston rotation as in the rotating pistons fitted to rifles like the TX200/Prosport and LGV/U then no they are not designed to rotate, it will be the maxigrip and the cocking shoe stopping it from rotating.
As for the spring, it may work, if it fits in the piston then it should be ok as for power then you can only tell after it's been fitted and chronoed, it's just trial and error I'm afraid.
Pete