question about spring rates?

[ArisESQ]

Hey guys,

So I'm finally getting ready to tune the suspension on my car in the next couple months and was wondering if anybody here knew a way to calculate the apropriate spring rate to go with front and rear, or knew what spring rate I should go with in general.

The car is a 67' camaro with:
aftermarket C4 front clip with QA1 coilovers
DSE quadralink with the koni coilovers

The car is tubbed, so I do plan on running a 335, and also plan on running a 265 to 275 in the front if I can. (not sure if any of that matters when it comes to spring rates, but I figured that it wouldnt hurt to throw that in there)

As for what the car is built for, it will probably be driven mostly on the street, HOWEVER; it WILL see track time in the form of track days and autocross as often as I can, and it will have a set of slicks to run. I am 100% willing to compromise ride quality for performance.

Currently the QA1 have 12 inch long 350 lb/inch springs in them. I spoke to a few guys that autocross their cars, and they suggested that I go with spring rates in the range of 500 to 600 pounds/inch. Should I even stick with the QA1 shocks? I'm open to ideas.

I'm unsure as to what spring rate DSE uses on the quadralink, but I thought it was something like 300 pounds? Anybody know for sure?

Hopefully I'll have my car in the street again this month! I'll be sure to post some pics. It's been a loooooong time since I've driven it.