Brakes pulling to left

A few things to check:

Most brake shoe sets have 2 different length linings. You have to look close to notice. The longer lining goes on the aft side on each wheel (front and rear). If you had all short linings on one side, that side would be weaker.

Insure your self-adjusters are on the aft side of each backing plate. You can find photos posted here, plus look at the factory manual. I think the adjuster should be tight against the star wheel to hold that position. I used the later style adjusters on my 65 Dart. They have an in-line spring instead of the torsion spring. Not sure about 1972.

Both of the above were wrong on the 64 Valiant I bought, plus somebody stuffed the "grease catcher" cup on the backing plate with fresh grease so it got on the shoes. All parts were new and clean so I put it back right.

Drum brakes are much more fickle about the coefficient of friction than disk brakes. That is due to the "self-amplifying" effect of the shoes jamming against the drum. A little leaking brake fluid can gum up the shoes and make them self-lock. Always clean the shoes with brake cleaner as a last step since even a greasy thumb print can make a big difference.