Aaron, I would look no further than ECE for your shock relocators and super trac bar. I have used all of their suspension components on my '69 and wouldn't have done it any other way. Everything fit like it was supposed to and was good quality.
You are correct in needing to remove your front wheel to determine the correct BS for you wheels. As far as measuring the rearend, let me see if I can locate the rearend dimensions on the board (unless someone else can chime in with them). I can't remember if you can just measure from backing plate to backing plate, and then how they compare to the years. I'll see what I can drum up for you...
Love the color combo by the way.
Cheers!
Nate