Tire size/type ideas?

One more thing, I cant really ask how much you weigh so I'll say this, uness you are a fellow person of substantial weight, you probably don't wanna run the superstock rear springs. My dad says my car rides to rough like a 3/4 ton truck but I find my suspension firm but not harsh and I have over 100lbs. On dad. When we ride in the dart together it actually rides like a car lol!

You were pointed to Espo springs n things for new rear springs, check out mancini racing for their OEM XHD springs. +2" should set the back of your car where mine is with a softer ride.

Ive had the Mancinni XHD and Mopar 002/003 SS springs in my 68, the XHD rode harder, with that said ive removed like 300lbs and the SS springs ride real nice, problem i think most people have is the shackles are binding causing rough ride.

I also have a pr of 002 springs in my swinger, with 1" bars and it rides awesome, not rough at all.