Well, LOTS of new info from Terry. The car was blue with white top when Bob bought it, BUT it had the white interior, contrary to the trim tag, which calls out black. He called another friend who went to school with Bob and he confirmed the interior was white when Bob got it.
Bob had it painted Black and a Black top, eventually, installed.
NOW, Bob had a control freak wife who never let him spend money for repairs or maintenance and Terry said the car will vibrate at 55 plus mph due to, what he believes, is the input shaft/bearing in the trans. This could, also, be as simple as a seized u-joint. Terry also said the car would wander and not handle very well when he drove it. He thinks the steering will need repair.
Unless the dealer did any of these repairs, the car needs mechanical work to bring it up to safe and reliable driving condition. This isn't a car to buy, sight unseen, the potential buyer needs to inspect and drive in person, or have a reputable third party evaluate it. Could be why the price seems a little low for a low production number '66 SS convert.
Still no idea from Terry or Darcy how the LS6 got in there. They were always of the belief it was an L72.
Bob is a little younger than me and would have graduated in '71-72, so the timeline fits that the LS6 could have been in there all the time and Bob just believed it was a 427 because of the emblems...