The ideal motor and ESC for your application depends on how much you can spend. You could go with a Quark Monster 125amp ESC ($280) and a Lehner 1940 motor ($285), or you could use a less expensive setup.
SH Z-Car, Custom Crawler, 8s Savage, 12s XTM XLB 1/7 buggy, 4wd 4-link rear/IFS Pro4 truck, Custom Hyper 10 Short Course, Belt-Drive Mammoth ST 1/8 truggy, 4s 17.5 MM Pro HPI Blitz
Your setup is a little expensive for me. I thought to put a Lehner 3100 on it with a less expensive ESC, but which one ?
And about the pinion gear, how much tooth must I choose ?