Suspension/Chassis Suggestions - 70 Dart Swinger

get 6 leaf HD springs for the back, front, I upgraded my 6 cyl to .92" t-bars and really like them, they match well with the 6 leaf rears, and aren't bad even with the dreaded kyb shocks.

ROT is you want the front/rear ride frequency to be about 10% of each other. with the .92" bars, the rear calculated ~10% stiffer for me, with the 1" bars, the front will end up being the stiffer side and likely have the higher ride frequency, but a lot of it depends on weight distribution. my no power anything slant is lighter on the nose than a BB with PS/PB would be....
Wheel Frequency Calculator

my t-bars were NOS on a member's shelf, if you can only find new, 1" would probably be OK and still match decently with the 6 leaf HD rears.

I also added a helwig front sway bar, that made a massive difference on the feel of the car and how it goes around the corners, no more door handle dragging.