Best 1/10 buggy motor?

[Sylvester]

hey guys, im currently running a mamba max 5700 system geared 20/84 in a b4, the esc doesnt get too hot but i cant say the same about the motor, so im on a search of a better motor.

I was thinking of a Neu 1506/1y/s 5500kv as it would be closest to a 5700, the only thing im scratching my head against is the 5mm shaft, and way to get around this?