Writing everything in C first is like building a house by forging your own nails. Yeah you learn a ton about how the metal works, but you're gonna be 60 before the roof is on. Your uncle's advice isn't wrong exactly, knowing what's happening under the hood makes you better at any language, but doing a whole semester of it as your default way to work is a waste of your time. Most real jobs out there are shipping Python or JavaScript or Go, and nobody's paying you to rewrite a REST API in C because it feels more pure. Learn C so you understand memory and pointers, then use it when you actually need it, like embedded stuff or drivers, not as some kind of purity test for every project.

Used parts can bite you in ways new ones won't, and a carb is a bad place to find that out. A junkyard carb might have worn throttle shaft bushings or a warped base plate you can't see until it starts sucking air and running lean. Two months is not much of a test, especially if you are not daily driving that truck. I have watched guys chase a rough idle for weeks because they trusted a cheap used carb that looked fine on the outside. Rebuild kits are not cheap, but at least every gasket and needle is new and you know what you have. Your mileage may vary, but I would rather spend the $60 than roll the dice under my hood.