[WyoRoadDog]

As for going 69+ brackets, etc. that's a question for someone more familiar than me with the year differences. I don't know if you could or where you would mount the hangers to use 69+ springs. I would think you would have to move both hangers for the rear spring, since the pin location on the later springs is offset. Something to check, my springs were ~56" eye to eye, with the pin centered at 28".
Here's some more pics of the shackle flip setup. You would grind the rivets off and remove the original hanger. The new one bolts on, and there are 2 holes to be drilled for each in the bottom of the frame. As well, I modified the bracket to clear the rivet on the cross brace. Someone else may be able to say if that x-brace can go away.
If you look back at my other pic, looking at the shackle, I had it built wider than normal because '67 stock springs are wider than the '69+ that it is normally made for, then, at the top where it mounts to the flip, you can see where its kind of "shouldered". That would be spacers that Kert welded in to make up the difference in width from the spring to the bracket.
Hope this helps.