A factory service manual for any 68-70 B body will have a chassis diagram showing various measurements. THESE will help to determine if the frame rails are square and parralel.
It may be stating the obvious, but with a few bent parts, it can be difficult to get within spec.
Sorry, I didn't click on your link to see what you have done, but I'll guess that you are a "hands on" guy. You are probably capable of getting the car pretty close with a few basic tools. I set up the upper control arms as follows: Rotate the REAR alignment cam to allow the rear bushing close to the engine, and the FRONT bushing toward the fender. If the camber looks too negative, adjust the rear cam only. I hope this helps.