The presence of D55 on your trim tag means that D55 was now a separate option, as in after the A51 Sport Option was cancelled. Confusingly, now A51 RPO code now stood for Strato Bucket Seats, with console becoming a separate option that would be coded on the trim tag. The car sounds like a Beaumont Custom Sport Coupe 8 cyl, Nantucket Blue with medium light blue vinyl bucket seats, console, Powerglide. It could've been either a 283 or a 327, the tag won't say. The original engine code will be K mmdd DE for a 283 Powerglide, or K mmdd EE for a 327 Powerglide, really simple.

Carl's info on the date code on the trim tag is bang-on. I would expect your car to have the body bank # (shift-month-day) to be late November, like the 18th or 19th at the very earliest.