Anyone Lengthen Their Wheelbase?

I have a 68 Dart. I'm thinking of lengthening the wheelbase 2" so my rear slicks will center in the fenderwell. Was wondering if anyone has lengthened their wheelbase and if so, what were the issues.
all i did was weld the hole in the spring perch and redill the perch 3/4inch forwardand slid the rear back to center that axle seams to be ok