Asleep at the Wheel, the Western-swing band launched in West Virginia by Ray Benson and Lucky Oceans in 1970, was calling San Francisco home in ’74, when two Texas musicians suggested they relocate. One was Willie Nelson, the other was Doug Sahm of the Sir Douglas Quintet. “Doug was my good pal and Willie was my hero. Willie said, ‘Hey, I’ll put you on shows,’ Benson remembers. “Of course it didn’...