Well the first thing that popped out at me was the 30% for the 340 option.....that according to NADA guide shouldn't have been included.....
"1968 Plymouth Barracuda Formula S 2 Door Fastback (340) Note: Engines listed in parenthesis after model: Do not add for engine in option section. (i.e. 2 Door Sdn (440) - includes the 440 engine.)"
Next: some interior parts still need restoration and that right there would knock it out of the "high retail" down to "average retail" category.
Which according to NADA guide would put it at about $14950....