Adam McKay has cast Jason Clarke as Jerry West in HBO's hour-long drama pilot Showtime, which examines the Los Angeles Lakers dynasty of the 1980s, Collider has learned. Showtime is based on Jeff Pearlman's non-fiction book of the same name, which chronicles the professional and personal lives of the Showtime-era Lakers -- a team that defined its era, both on and off the court. In addition to West, key characters include Dr. Jerry Buss, coach Pat Riley, and All-Star players like Magic Johnson, Kareem Abdul-Jabbar and James Worthy. There aren't many established Hollywood …