Not to nit-pik, but the MSD 7 was available before 1977. I had one on my 65 Valiant Z/sa before 1977. I think it was 1975 or 1976. Had to special order for the 6 cyl, not a 8 cyl. and it did not have the Chrys connector. It had a terminal strip, and was wire with direct wiring.
PS: I still have it on the shelf. It died about 10 years, ago, and MSD said they couldn't fix it (part not available). A member on slantsix.org, had me send it to him, and he was able to repair it for $25.00. Transistor went bad.