1) What are the advantages and disadvantages to having the leaf springs mounted parallel to one another as opposed to spread wider at the front than at the rear?

2) Should a pair of leaf springs when removed from the vehicle maintain a matching arch or should the passenger side spring (Superstock 456/457) display a higher arch? I hestitate to bother installing them with this discrepany.

FWIW, Application is a 73 GTX used primarily as a drag car with limited street use.

Any thoughts?