[L79racer]

I just put Landrom 16" tall 200 lb springs in front of my 66 Vette. It compressed them down to 10 3/4" so, 5 1/4 times 200 is 1050lbs. I say your suspension is bound or springs arent into pockets correctly.

Just wanted to add, you should check the ride height of the shocks after you get the springs figured out so you know how much compression and extension you have for your shocks.
Set the car on the ground with no shocks in and measure the shock mounting points.