64 pitch gears have a larger pitch diameter than 48 pitch gears. In other words, to get the same gear ration the motor is going to be more towards the outside. (basically larger gears.)
And no, 30-32 for a stock motor on a large track is just right. 28-30 for a 19 turn is good. 26-29 for mods. with 72 tooth spur. I run a 75 tooth spur to move the motor more outside to counter balance the weight of the batterie, and for a more efficient drivetrain.