Hi!
Mike can get you a motormount for your savage. that's not a problem.
The A123 cells should be run in 2P, otherwise they are too weak, they drop too quick in voltage. About your overgearing question; Get a tempgun (they are fair cheap) and measure the voltage of the packs/motor/speedo.
Check this thread;
http://www.rc-monster.com/forum/showthread.php?t=2200