Rear suspension help

[l8rg8r]

I want to run 295/50/15 on the rear of my 68  rr . they fit but are a little to tite on the outside lip of wheel opening. I want to lift the rear but I am not sure how much I should lift it or what is the best way to go about it .So what have you guys done ? Whaat was the outcome? How did the car handle when you got it done? Thanks

[terrible one]

To start, definitely lift it with the leaf springs. . . perhaps a stiffer spring like the HD, XHD, or Super Stock springs . . . or maybe simply get a custom spring made with more arc? Either way, don't do it via shackles or air shocks.