Old style drum brakes are perfectly good at stopping the Volvo as long as they're in good condition. Drums are very expensive, so it's important to replace worn shoes before they wear down to the rivets (and the rivets damage the drums). Also, if the shoes are contaminated by brake fluid, they should be replaced promptly.
Sold in sets of 4. (To repair/replace one axle set)
Brake Adjusters: The “square head” adjuster fits many 122 and 1800 models from 62-67. These cars need manual adjustment of the rear brake engaging point. Since most of us neglect to do this as often as we should, it’s pretty common to find these rusted and stripped. Easily identified by the square head adjuster poking through the backing plate. Yes, you will need a brake drum puller to complete this repair.