Inside, the front office near the receptionist’s desk there are vintage copies of Jet and Ebony, magazines geared towards the black population. The switchboard looks like something out of the original “Dragnet,” with quarter-inch plugs and manual phone patching to route calls. Upstairs, Gordy’s apartment has a crib for his sons, and the kitchen is ready to provide either the family dinner or snacks for the office workers. The living-room table is stewn with records and surrounded by boxes, just as it was in the early 1960’s when ....