The game is balanced at All Pro at settings of 50...with the possible exception of fatigue,
these settings are completely independent of quarter length.
The math just doesn't work this way...you will completely change the dynamics of the entire game with these changes, will wind up with no penalties called and because of the low injury/fatigue/thresh values, you will wind up in shootouts virtually all the time.
I'll give you credit for creativity, it just won't give you a realistic experience.