Chopping down a 9" small web
 

I'm going to run 15x14's, and probably 31inch tires. I was wondering were to start to narrow it down and how. It's a 69 chevelle with 4-link suspension and I'm going to run drum brakes on the rear. Any help would be great, like pictures or sites that show you. Oh and the rear of the car is all tubing and currently have a 12 bolt rear end with a positive off set. Oh and what back spacing should I run? thanks