Sounds like the wheel back space change should work well according to my math.
It should move the tire 1/2" outward with the new axle and 5.5 backspace wheels.
Any pics of the 245/60/15s on the car? That's the same size we're looking at running, or a 255/60/15. Along with offsetting the springs inboard.
Thanks. Enjoying following the build. Great work. Eric.