Need some suspension/chassis guidance
My opinion would be mini tub it, buy the wheels and tires that will fit with the offset you like. Put them in position, and measure from the back side of the wheel to back side of wheel at the mounting flange. Have the rear cut so it's that measurement axle flange to axle flange. Have the spring pads moved to the width of the springs that you moved. Allow for room between the tire and the fender and spring.
This is what I did. Except the 68 Barracuda stock tubs are big enough to accept the 325/50-15 DRs, and I only needed to move the springs over with the offset kit. My 15 x 10s have a 4.5inch backspace. This is common amongst 15s and makes changing wheels later, an off-the-shelf deal.
My car is lowered some, with nearly flat leafs, and the 325s did rub with moderate cornering. They only rub in one same place on each side. I have beat that area heavily but there is "something" behind the panel that refuses to to be moved.I think it's the shock mounting bar, but don't recall(was 12 years ago).So I moved the wheels over with 1/8 inch spacers, and trimmed the outer fender lips. Now is good to go;mostly..... At stock ride height, I don't think it would be an issue.
Be advised that the rear end may not currently be centered in the car, so order your rear a bit narrower than you measure, and do not have the perches pre-installed. Then you can mock it up, center it, set the pinion angle, tack in the perches, blow it all apart, and final-weld it. I had allowed 1/4 inch for spacers, and used only 1/8; so had I ordered exact-fit I would have been 1/8 too wide. But here's the thing, if the rear ends up too wide, you are sorta screwed, needing new wheels. If it's a hair narrow, you can just space the wheels out.
Of course all of this is moot, with mini-tubs.
In about 1979 I purchased a 74 DartSport 360-4spd. It came with N50-15 Pro-Tracs; remember those? The tubs were stock. The wheels were Keystone 15 x 10s.The rear was raised some. I don't remember how big Ns were, but I think they mightabin pretty close to 325s, but closer to 60 series. I do recall that the treads were inside the fenders, although the sidewalls were closer to flush with the outside body line.The cops made me put mudflaps on the backside. Those tires didn't rub on anything. But with the back up, you couldn't push it hard around corners anyway.
Point of story is this; Ima thinking DartSport tubs are same as or similar to, the 68Barracudas
