If you dont have plans to mini tub then just get the offset shackle kit from Mopar Performance. It will move the springs enough to allow you to use the entire wheal well. Usuallyu about a 26 or 28 X 10" tire. If you use the weld in kit you wont gain any extra over the offset shackles without mini tubbing it.
When I did the spring relocation on my Valiant, I bought one of the spring kits I now sell - ended up selling the car (poverty sucks!) before it got the wheelwells done.
But having the 'whole meal deal' on spring relocation was a plus when I went to sell it, because it left the upgrade path wide open. At least as wide as between the rails and the quarters...
It's also going to be a plus when I buy it back this spring. Man, I've missed that car.
I just ordered my relocation kit from bill at THE CAR FARM. These are shaped to match your frame unlike the mopar performance ones. Kit is about $119 or so. I cut out my wheel tubs and should be able to fit 325 50 15 in there. I have some 12" slicks that look like they will fit. Why would you do the relacation and not the wheel tubs? jared