New Mopar Addict

Keep it simple. Work with the factory stuff especially when the numbers are gibberish.

Get a Factory Service Manual. It covers a lot of rebuilding. Some years are free downloads at mymopar.com
IIRC there is a 65 or 66 there.
Print copy is nice too - keep an eye out for them.

A compression test is useful if you can turn the engine over with a starter.
A leakdown test is a bit more useful.
Look for a copy of Taylor and Hofer on rebuilding small block mopars. Because its out of print and some sellers think its worth $100 but eventually find someone selling a copy at used paperback prices.

Avoid youtubers. Its mostly entertainment. At this stage there's little for you to judge if they are actually providing good advice.