It would help to know what the chassis front suspension set up is like. Does the car have parallel front leafs like the older Chevys or does it have a transverse leaf like the early Fords used? either way the right side will need to be stiffer than the left side by about 50 to 100% depending on the track bank. With a parallel leaf set up this is fairly easy. You just add or remove leafs to get the spring rate or handling feel you need. On a Ford buggy spring front end it gets a bit more involved. One of the most successful transverse front set ups was called the Flemke Front End named after Eddie Flemke, a modified pilot from Connecticut. What he did was basically cut the single spring in half so each side could be different. Each side also had a jacking bolt for adjusting wedge and ride height.
This set up also involved a special front chassis pad be made up that had 2 center bolts and 2 more U bolts to locate and hold each side of the spring. Radius rods also needed reworking to keep the axle from wobbling on the now cut in half spring. To get an idea what this looks like check out some of the ads in street rod magazines.
There is an independent nostalgia front end being offered that uses this type of spring set up but the beam axle is also in 2 pieces, the Flemke front end used the axle in one piece.
As far as actual spring rates go you can't use the formula for rating coils. Leaf rates change as the spring deflects and is also effected by the amount of travel the free end shackle allows. Toss in a jacking bolt somewhere on the moveable part of the spring and things change again as you have actually shortened the spring.
Tapered leafs and mono leafs further add to the mystery.
good luck with the project,
Mike
