I am planning on seeing if the engine is able to run before sinking a bunch of money into it. The only part I have bought so far is the oil connector. I spent the weekend cleaning sludge off the head, rocker assembly, and lifter rods and under the side cover. That's when I noticed the well-worn shafts. Assuming the engine works I wanted to have some idea of where to buy replacement parts. Truthfully I don't know much about all the different tests you mentioned but I was planning on following the stovebolt guide here - https://www.stovebolt.com/techtips/engines/Dead%20Engine%20Start/index.html

I have a neighbor who knows a lot about these old trucks so I've also been relying on him to guide me through this process. The engine turns with the fan blade and you can feel and hear air whooshing out of the spark plug holes so hopefully those good signs point toward a working engine.

Thx