Newbie, with questions....

That's a cool looking ride, and welcome.

I'm not familiar much with what disk brake set up to use on the early darts but I personally used the master power manual disk brake set up on my car. 67 cuda.

A little pricey but stops much better than drums.

Some guys are using the scarebird stuff, others are using ssbc, baer, and wilwood.

If you are patient I'm sure guys with the early A's such as yours will chime in with their improvement packages.