My new 1968 Nova L79 project.

[Schonyenko2]

Appears your information from the original owner is right on. I thought perhaps that if it was blown up early, and bad enough, that it might have recieved a engine replacement. Some of those had the correct pad stamps, for example CTB for a 4 spd deuce, but no sequential vin nbr.
I wonder if he wanted a 396 with air, but when told that wasn't available, settled on the next highest hp rated motor he could get with air. Always interesting to find the reasoning why people ordered cars the way they did.