Starting point would be to just tell them you want factory style xhd E body springs, stock height, and then maybe outline whatever plans you have for it horsepower or handling wise and they can give you recommnedations from that point.
The thing about mopar springs is when they are installed, they should have very little arch to them. At proper ride height you might have about 2" of arch to them, which to many will appear darn near flat. The oval track handling springs were actually offered in 1" and 0" arches.
Bushings wise, your intended purpose may be used to decide which ones provide the best benefits. Rubber is comfortable, poly is firm with minimal deflection, aluminum or bronze are dedicated race parts.
