How-to: Damper selection for custom build

I have slashed an E30 down to 2000lbs, caged it, reinforced the rear shock pick-ups to handle a true coilover and stiffened the bejeebers out of it with a cage tied into the front towers, rear towers, diff carrier, etc.

I plan to use full threaded-body 2-way adjustable dampers from QA-1 or similar but... how do you calculate a starting point for amount of spring and the valving you need to control it? I can easily get the coner weights, etc... and can guess at the spring rates from feedback from others... ask the damper vendors about setup but I want to know for my own edification... how would I go about this if I made my own chassis?

Figure the spring rate (or get in the ballpark) by calculating the suspension frequency, then tell the shock manufacturer and have them valve the shock to suit. Carroll Smith isn't in to figuring frequencies but it's a good way to start out.