Dcmgt,
The original suspension bump steers enough that your Ackerman will change with ride height and roll. You need to get a handle on the bump steer front AND rear before you can do any meaningful calculations on Ackerman. Another problem you have is the rubber bushings in the rear trailing arm flexing under braking and acceleration. A good program for doing the calculations you need for the front is WinGeo3 by Bill Mitchell. His web site is
www.mitchellsofware.com Note his software (nor anyone else for that matter) will not do the rear suspension for an original Cobra.