Don't forget the driveshaft length. There must be a way to move the whole driveline back a certain amount. If you can find out how to move the motor say 1/2 inch, then you can probably go the full inch and still not hurt the weight distribution much.
If it isn't feasible to move the motor, I would still consider moving the axle back anyway. If you get good weight transfer, the car doesn't care how much is on the front Vs rear.
I went from 50/50 to 52.5 front 47.5 rear and was really worried that it wouldn't work there. Works great. However you have to have enough torque to maintain that weight transfer. Bigger tires can overcome this, and going faster (more torque) will help as well.