The A actually has a pretty darn good suspension design, it's just pushing 60 years old.
All the normal stuff applies-
Subframe connectors.
Heavier torsion bars (over 1"- 1.08s are the popular go-to).
Fat anti-sway bar (Hellwig and others have good ones).
Box your lower control arms.
Clean and fully re-weld all the seams on your K frame. Weld reinforcements around the steering box mounts.
Consider welding in the chassis stiffening components from US Cartool.
Rebuild the front end with GOOD parts- poly if you don't mind the harshness.
Adjustable upper control arms and struts.
Then get a real front end alignment from a good shop- and throw out the factory specs. Use the SKOSH chart instead, here:
Following the SKOSH chart - your experiences?
Of course, bigger and better brakes. Lots of ways to go depending on what you want and how deep your pockets are.
And then there's tires, tires, tires.
And that's just touching on the front end, you've got the rear to think about too.
LOTS of good info on this forum about it all, use "search" in the suspension forums and you'll have enough reading to keep you busy for a week.
And it's not all a matter of throwing high-dollar stuff at it, you can build it into a slot car with wise part choices, some factory part swapping, and a clear goal.