H&M M-1 Supercat

[10gauge]

My design goal is to make a 70mph 34" H&M M-1 Supercat. Question: Which would be a better motor for a 6S setup, a Lehner 1950/ 9T or 10T?...

I am planning to use:
Hydra 240 ESC
6S2P 4300 mAh Neu 25/50C LiPoly -or- 3S2S Neu 25/50C (4900mAh)
M645 or X447 prop
Hardware: Direct drive, FDM 21EGSRA Strut/Rudder.

Thanks guys!