Leaf spring theory question

I have a b-body with the rearend moved back an inch, with super stock springs and hangers, hanger holes modified from mopar supplied location. All i know is what i see on my car.
1. Yes, more rear shackle angle. Not a problem in my experience.
2. Ride height was modified by lowering the drilled hole in the hangers, in an attempt to reduce rearend lift at launch, altering the theoretical instant center.
3. One inch longer driveshaft.
4. I dont know about arc of travel. I DO know (noticed just the other day) that when jacking up the front of the car, the rearend RISES, contrary to expectations. ( i would have thought that weight transfer would cause the rear of the car to settle) I think that is a function of the super stock springs