IMHO if you are going to go that far I'd start with the US Car Tool kit to move the springs into the frame. Since their kit uses the original spring mount holes to locate the new pieces there is a lot of guess work eliminated. If you don't get it right and the springs are loaded in one of two directions your car will NEVER hook. Once you move the springs in there's no real need to narrow the rear end, just move the perches on the housing to fit the new spring spacing, and then get wheels with the backspacing to use the new room you have created.
As far as springs go, my favorite is ESPO 6 leaf springs and add an inch so when they settle (a year or two) they will be at the original stock ride height.
