did the 68 gt/cs ever come with high back seats or is this an after thought by somebody???

By "high back" seats, do you mean the seats with the head restraints? If that is what you meant, then yes, it could have been ordered with it. If that is not what you meant, then no, there was not a high back seat that I am aware of.

I believe that was not an option until '69. I had a '70 with 'em. If you see the tall seats in a '68, they have been replaced! A Cal Special went for 12,900 on Ebay a few months back. Had a 390 and I believe someone here bought it. It had high backs, but you could tell he had swapped em