Somewhere between Elvis Presley’s honorable discharge and his immediate sequestration under Colonel Parker’s fleshy, bejeweled wing, there existed a window of opportunity. What if, instead of “Paradise, Hawaiian Style,” we’d heard a deeper exploration of country and gospel music; what if he’d been backed by the Funk Brothers or the Wrecking Crew; what if Americana hadn’t come to mean either at best a rote recitation of Old Time music or at worst a bland...