Since (cents) you are already running Bilstiens, and you didn't state your intentions, ride or handling are a little of both, I would suggest a stock front spring and cut 3/4 to one coil. On the rear look into a TRW spring #5401. TRW, Dana, Perfect Circle, Napa are all the same #'s.
front
GN or T Type Front Load Rate load hgt. Free Hgt.
TRW # 5606 1530 lbs 420 14.637"
IROC Camaro
TRW # 5662 1690 706 13.149"
As you can see the Camaro spring is shorter. Wherein the load carrying isn't too bad, the rate load is very high. Global West and Hotchkis front springs are in the 550 to 600 lbs range, so that should tell you just how stiff 700 lbs is. Another problem with going too stiff on the front, aside from the hard ride, is the front will 'row'. This is similar to what the bow of a boat does going thru water, an up and down movement. It is small but noticeable, and the stiff Bilstiens will aggravate the problem. What is happening is, instead of absorbing the small dips and imperfections in the road, the front end follows them
REAR
All Regals
TRW # 5379 759 121 14.768"
My Choice
TRW # 5401 726 128 13.159"
As you can see, the 5401 is shorter by about 1.6" even before you install it. Doubt you will notice the difference in the load.
Hope this helps
