How to make this Dart Handle?

All the aftermarket parts you can buy wont make a 72 Dart into something its not. You haven't mentioned sub frame connectors which are a very important part of the chassis that is lacking, along with vehicle balance, center of gravity, aerodynamics, etc..
I not saying there is anything wrong with building a old A-body to be a curve carving road course car but... there is a lot more to that than just strong springs and things.
You could very easily end up with a car that drives like a truck for your daily driver.
If you want a car that takes to the road like a Porsche,
best money is spent on something like a Porsche. At least you can get your money back someday.
I haven't seen too many buyers in the market for a classic Dart that drives like a truck.
Depending on what the Dart has or doesn't have now, you might vastly improve handling with very simple, less expensive upgrades, 73 up K member with the stock sway bar through it is a good example.