You only need a recovery tank if you’re using a sealed system, most of the older cars like yours were an open system (purged to the ground). In a sealed system the radiator purges to the tank then recovers the fluid on cool down. A sealed (recovery) system will maintain the coolant levels and control the air in the system better than an open (non recovery) type. Less air less = better cooling transfer and less corrosion in the system.

If you decide to add the recovery tank you will need to replace the radiator cap with a recovery type cap of the same pressure your system is operating at presently. Careful, do not increase the pressure cap higher than what the radiator is rated at, it can damage the radiator.