if it is only an inch difference your drive shafts should have enough slip in them to compensate. If not at least for the rear you could use a zero rate and move the axle back 1 inch that would help your departure angle
well im thinking that with the addition of an 80e, my friend had to change his driveshafts due to overall length increasing. by slotting the engine forward 1", it would hopefully offset the change enough to not need driveshafts. i would use a zero rate but i'm actually lowering the rear down a bit and its a total street queen so i want to keep it centered in the wheel well, no real need for good departure angle