1.5" narrowed rear end question?

[Gibson68]

I have read a few threads on guys narrowing the factory 9" 3/4" per side but I am wondering how much clearance is between the inside of the tire and the wheel well. I know the clearance will change depending on wheel backspacing and tire selection. I plan to run American racing 15" full polished salt flat special wheels which are custom ordered. Is 3/4" per side the max without suspension or wheel well modifications?

[RICH MUISE]

I'd have to go back and check my backspacing, I think they're 4.25 on the back wheels, but 3/4 per side narrowing works out perfect imo...at least it did for me. With that combo backspace and the 3/4 shortning, it centers the wheel inside/outside.Any more and you start running into clearance issues with the springs and other stuff on the backside of the wheels. I'm running 2.35's on the back and have over an inch clearance to the unmodified wheelwell lip and about the same on the inside. Next tire change I should be able to go to 255's with no issues, and with other stuff I did, absolutely no tire changing issues.
Sorry my memory is so bad, but I can check back to see what all those dimensions were for sure. Backspacing is the critical thing on your wheel selection...more than a few  of my choices turned out to not be available in the backspace/wheel width I would have prefered.
Several things to be concerned with before you have the case shortened: if you're considering a brake update, be sure of your brake kit selection and what flanges are required. Changing to discs will give you more tire changing room. If you're rebuilding the rear suspension...consider the 6 leaf springs. They give an added 1" lift comared to new 4 leaf, and use '56 shocks...they allow the rear to drop another few inches which is a huge help when doing a tire change.