Suspension upgrades

Pretty much stock under there. I did put one of those rubber kits in 20 years ago. Going to bbp, disc brakes. I realize the link I posted is way too much, and I really do not know what to replace to achieve what I want. There is an Auburn pro series sure grip in it now. I have a set of TTI headers in a box. Air gap on the old motor and a 750 Holley waiting. I want it to stop better and handle more like a newer car. So, where do I throw the money. I do plan on putting better heads on the motor. Your suggestions on "easily achieving that goal with half as much" I admit I am no expert on the subject, so I am interested in suggestions. Any money I do not put into the suspension will go to the motor. Thank you for your help.
Sparky
you have a formula S already, so you should have a sway bar... that's half the battle right there.

26 doubloons is a grip to flip if you're just looking for something that handles nicely. you could easily achieve that goal in half as much.

what else have you got going on suspension and brakes wise? I guessing it's all S, but a lot can change over the years.