There are most definitely 1970 LS-6's that came with bench seats and column shift. I've seen two documented LS-6 cars that were this way. The floor shift and bucket seats were always a separate option, regardless of the motor, or whether or not it was an SS.
One of them came out of Floyd Garrett's Muscle Car Museum about 2 years ago, it was featured on My Classic Car TV show last year and was at Autofest 2000 in Evansville Indiana. Beautiful car, fathom blue, blue interior, white stripes, bench, and column shift.
Another is owned by a doctor in the Dallas area. I spoke to him a little less than a year ago when he had it for sale on Ebay. A true sleeper, this one was even ordered with the "stripe delete". It was a red SS with LS-6 motor, bench seat, and column shift. Fully documented. I don't think it ever sold as no one met his reserve which must have been in the mid 30k range.
Bob Von Kaenel
70 SS 402ci TH400