Bulova 1977 Accutron Calendar

This is indeed unusual. The only watch I find in the 1977 linebooks that is a partial match is the one shown below. It appears to me based on the unusual cutout for date window and the overlap of the indices into the current open center, that this is a match.

I am guessing that your watch had the dial removed and perhaps the day wheel. Either that, or the movement is a replacement with only a date complication.

1977 Accutron Date & Day 21542-6W w/Spaceview modification

Anything is possible, but due to the lack of the day wheel, I'm more inclined to think it's a mod of a watch that had mechanical issues. Removing the dial and day wheel would be a quick fix to make the watch sell-worthy, instead of a watch in need of potentially costly repair.

My other choice is a watch with a bad movement that had a non-day date only replacement movement installed using the original chapter ring and removing the dial due to the empty day window with a non-day movement.

The only Accutron "display watches" I'm aware of were provided to dealers very early in the release of the technology (early 60's) before day/date examples. This is my opinion and not backed by any confirming data. Be patient, I'm sure other panel members will be commenting on this one.

I suspect that this is a calendar version of the Linebook entry shown above and that the inner dial is missing. Someone may have removed it to show the inner workings.

I would classify this as a Non Standard Accutron (Non-conforming) It's unusual presentation leads me to be hesitant to classify it as anything other than a modified watch. It is unusual and if you're looking to purchase an odd watch this could be it. It is not a factory made display model.

If anything could we not ID as a generic 1977 Bulova Accutron Calendar?

1977 Accutron Calendar  works for me noting dial and day wheel removal and likely replaced hands. I will also note that the only use of this case with crown at 4 o'clock and radically notched chapter ring calendar window in it is referenced above from linebook.