Have you searched 3rd gen ruf pack setups? i believe thats the rear spring pack your describing.
You are correct it is a 3rd gen set.
I am fixing to start the SAS on my 88 4Runner and I am going to run fears up front and 63 chevs out back. The truck didn't come with the stock rears. So I picked up a set of rears from a 92 truck that my buddy had layin around. They are 3 inches longer than those from a 88. So it's an inch longer on the front half and two on the rear half. Has anyone else gone with longer ruf springs? I know that it's going to require different mounting places than the shorter springs. I guess what i am getting at is: would I just hang the rear of the spring in the body mount like normal and push the front hanger 3 inches forward? What do y'all think? Open to input on the topic. 
You have the right idea. My buddy uses a piece or 2x3 rectangular tubing between the frame and front spring hanger to aid in pushing the front hanger forward. Just make sure you gusset everything when it is all together.
