You might want to contact Dick Guldstrand (the Corvette racer/tuner/builder) at Guldstrand Motorsports in Burbank, California.
His was one of theshops replacing burned-up Rolls engines in almost-new, just-out-of-warranty Rollers from Beverly Hills and Hollywood in the time period described above. He used new Caddy engines and could tell you what's involved in the swap.