Offset shackles
Those who may have "heard" rather than "done" it, may be incorrect. I've done it, and it is 1/2" per side, not 3/4".
That said, not hard to do, huge benefit, and if people really think springs 1/2" inboard will cause stability issues, well I don't know what to say. 1/2" more clearance in the wheelwell of a 67-69 Dart is absolutely huge.
Do it!