lehner 1950/6 on 14 cells?

I have max amps WCE 4200 7 cell packs. Will this be enough power for me? Also on the diffs, what diff the HB Pro or just the HB diffs? Im getting them here so?? 51/20 with buggy diffs What do I cal. the gearing on? Full volts or load volts? 1.0v per cell or 1.4 per cell. Will it also get more runtime? Im planiing to get 4s or 5s packs in the future. 5k to 10k mah idk I read someone got 35mins of runtime on 4k packs. (1940/7) Will the 1940/7 pull to much current from the MM? What hinge pins and diff oil do i need?