"Baselining" my 225

Bear with me here... I may get long winded.

Whenever I get a "new to me" vehicle, I like to give it a baseline tune up and mechanical going over. Never trust a P.O., right?
Now that I've got the brakes sorted, I'd like to start thinking about a base-line for the engine. While it seems to run good, I don't really have any experience with these engines and there are a few things the P.O. did that have me scratching my head.
For starters, I have a '65 Valiant and the engine seems to be from 1980. I know most parts interchange, but I want to make sure I'm ordering the correct stuff.

Here are some pics of the engine #'s and stampings....can anyone confirm that this is from a 1980 passenger car?

1965-plymouth-valiant (6).jpg 10PTIB.jpg engine #.jpg engine #1.jpg engine #2.jpg