I personally ran a GTB w/ 6.5 in my B44, on a medium size track, I also ran a SMC 7.4 2S Lipo Saddle Pack (had 2 of them). I don't remember the pinion I was using, but I want to say a 14 or 15.
I also use a Hyperion 0610i DUO charger (about $275), but I run 1/8 scale electric, and fly heli's.
There are cheaper chargers out there, but the one I have is one of the best. I know people that ran Mamba Max ESC and a 4600 or 5700kv motor, depending on track.
U4RC 2.2 Trophy rig by RCFab Works
Team Associated B44.2
Lost Eight 3.0e