I was a big Doug Furnas fan and still am. When I lived in Calif I was training once at Golds in Pacific Beach-right off the 5 freeway. This was in 97 or 98. The owner told me DOug lived in SD and had been in the day before and had repped out with 700 in the squat. I never got the pleasure of meeting Doug in person but I would have loved to.
As for info on Doug-I do not believe he ever authored a course but at one time in the 80s he and Ed Coan had a video seminar that was available through Crain's Muscle World-they have a website and the owner Ricky Crain could turn you on to some contest footage of Doug. The best footage I have seen of him was from the 1985 Hawaii Record Breakers meet-this is prolly the great contest ever-hatfield, Arcidi's first 705, Ed Coad going 2200 at 198-and Doug lifting huge weights effortlessly. Famous for his huge legs and squat Doug also benched 600 in a poly bench and shirt and deadlifted 821 once-one of the lightest guys to ever total over 2400 legitimately.
From what I know of Doug he was a fascinating and intense guy who once rode competitive bulls in a rodeo and became a powerlifter after a bad car accident left him in a wheel chair for a bit. Good luck in finding more info out about him and if you want any more info-private me please.