2 questions

Hi, I have 2 suspension questions that I'll need answers to. I think my leafsprings on my dart 72 is totally worn out. the car have a pair of "hijackers" air shocks in the rear and I testet to remove the air from the shocks to see how low it was without it, and it is like slammed without air.. :( The leafsprings doesn't have the "banana" shape at all.. It is straight.. Is the leafsprings that's on junk?
If I need to replace them, what should I get?
And I don't want it to be low in the rear.. More like high in the rear and low in the front haha but not extreme ;)

My second question is about torsion bars, right now the front end is extremely loose.. I want it kind of stiff. What size is to recommend with a small block engine?

Sorry for my bad English.. Hope you understand what I mean!
Regards from Sweden