rear axle spring perch flip

His car isn't low, I'd venture it's the same as your. Remember the Dart has the lower outer wheel lip, not arched up. Lower the edge of your lip 3" and it's about in the same spot as his.

Get the car together, then make a decision on where you want the rear to sit. Relocation and a mini tub makes it easy to stick tires under it. You really need to get the proper wheels so the tire fits the wells.

And also center the rearend to the wheel opening for biggest tire possible

My dads buddy run 295-75-15 with some rearched HD Mopar Springs and a 3inch relocation on his 67 GTS