I would get the Turnigy 50-55 600kv because it has the 8mm shaft. Use the RCM 8mm output yokes for the revo driveshafts and you'll be set. BTW: Just stripped out my 5th and final stock 3.3 output yoke today doing some testing. Im really getting tired of this... RCM 8mm output yokes are a must!
What mod are you talking about? Just the mount? Is $20 the lowest he would charge? I got a lot of stuff to buy. If you got any more sketches or anything on that mount please shoot it my way, I still need to see that it would work with those batteries.