My dad bought the molds from Don A. in 1974/5 - not in the mid 80's.
The hull mold was the Cigarette 24 and the deck mold was the old early 70's style (it used to have teak covering the whole front portion of the deck!) 24. If you search for some other posts on this, you will see some examples of this old style early 70's deck. I don't have a pic of this old style deck at hand but I'll look for it and post later...maybe someone else out there has one?
Don A. had more than one set of hull molds for the 24. In fact, Cigarette redesigned the deck for their 24 sometime later and that model was called the "Firefox". So to answer your question in simple terms, Yes - the 24' Banana Boat and the 24' Cigarette are essentially the same boat with different decks. And yes, I think Hal Halter owned Cigarette in '79 so yes he would have built your friend's boat. Do you have any pictures of that Cig. 24?
Don A. really liked and respected my dad as a racer and friend. He, Bob Magoon, and my dad even had the same special edition Mark Donahue Camaros. To my knowledge, my father was the only person that Don ever sold molds to instead of selling the whole company (i.e. Ted Theodoli & Magnum etc.) In fact, Don allowed my father's employees to come to Cigarette to learn first-hand how to build the boat. I have pictures of them at the Cig. factory learning how to do everything. If you are interested, I can post some of those too - they are pretty cool historically speaking.
I hope this answered your question...