As the debut season of the surprisingly entertaining Tony Stewart/Ray Evernham-led Camping World SRX Series nears its conclusion next week, we dive deeper into the rabbit hole of one of its major influences - the legendary International Race of Champions (IROC) - with longtime automotive journalist and former Motor Trend magazine Executive Editor Matt Stone (“The IROC Porsches: The International Race of Champions, Porsche’s 911 RSR & the Men Who Raced Them”).   As table-set in our previous Episode 173 with former Indianapolis and Ontario Speedway exec Dave Lockton, IROC was envisioned as the American motorsports equivalent of a major “all-star” showcase - pitting twelve of the world’s best professional drivers from racing’s top competitive circuits in a series of races in identically prepared and maintained cars, in an effort to test participants’ pure driving ability and determine the sport’s true “champion.”   Stone helps us with the backstory of IROC’s operational formation - brought to life in late 1973 by racing executives Roger Penske, Les Richter and Mike Phelps in the form of an initial four-race roadcourse series across Riverside international Raceway (three qualifying races: 10/27-28, 1973) and Daytona International Speedway (final: 2/14, 1974) - all televised in tape-delayed glory on ABC’s then-dominant sports anthology series Wide World of Sports.   Inaugural invitees: NASCAR Winston Cup champions Bobby Allison, Richard Petty & David Pearson; SCCA Can-Am road-race standouts Mark Donohue, Peter Revson & George Folker; USAC Champ (Indy) Car winners Bobby Unser, A.J. Foyt, Gordon Johncock & Roger McCluskey; and Formula One stars Denis Hulme & Emerson Fittipaldi.   And the now-iconic sports car initially selected to challenge them all: the purpose-built, virtually identical 1974 Porsche 911 Carrera 3.0 - all 16 originals of which are still alive, well, hugely revered, and highly sought-after today.