The claimed 585 hp is of course gross rating, the net rating according to a dyno test with proper exhaust, air cleaner, accessory belts and stuff is 376 bhp. With the Road and Track test car having a less than 3,000 lb curb weight and grippy tires the 12.1 at 116 mph is very believable. By the way, they weren't drag radials, radial tires weren't readily available yet in 1969. The first factory fitted radials in Mustangs and Corvettes came in 1973 and 1976 accordingly. That is if memory serves me right; and drag racers didn't go radial until the 1980s, I think.