what do i need to buy to put new brakes in?

If you want to replace everything and start from scratch, I would start from the ground up. If you want disc brakes you could get a kit like these:Mopar Chrysler Plymouth A body front disc brake conversion 5 on 4 bolt pattern | eBay

Complete Dodge Dart Mopar A Body Disc Brake Conversion Kit for 5x4.5 Wheels | eBay
Pay attention to the bolt pattern, I don’t know what yours is. There’s “small bolt pattern” (5 on 4”) and “big bolt pattern” (5 on 4.5”)
You can get a kit with or without a master cylinder.

And then choose a line kit. I like replacing my lines along with everything else because it gives me peace of mind:
1968-69 Dodge Dart Mopar A Body Complete Manual Disc Brake Line Kit Set OE Steel | eBay

I hope this helps. Of course, do some research to make sure the parts you’re getting match the goals you have. If you just want to cruise, keep it simple add a brake booster if that makes you feel better.