The Altec 515G (8G, 16G) works well in the four π or seven π cabinets. Response is just what you want for home hifi, slightly overdamped, much like the curve that results from a JBL 2226.The 515G is suitable for use in vented cabinets from 2.0ft3 to 5.0ft3 tuned to 40Hz to 50Hz. The lower tuning makes the cabinet slightly overdamped. A slightly higher tuning is best if the cabinet is used outdoors or in large spaces.
Note that not all 515 drivers have similar electro-mechanical specs. The 515B and 515C, for example, work best in larger boxes up to 15ft3.