Early A body rear end narrow questions

I used the offset shackles and hangers on my 66 Dart. I had the rear narrowed by a local shop and he had me fit the rims/tires in the stock wheel well and I measured and marked where the tire/wheel was centered and he narrowed it and supplied custom axles. Biggest tire I can fit is a m/t 255-60R15 drag radial. Stock wheelwell is a limitation for sure. But it hooks okay. best 60' is 1.88.