340 tune up

First download a factory service manual from Service Manuals – MyMopar

Do the basics, compression test, plugs, plug wires, timing, carb adjustment.

Transmission inspection / top off or fluid replacement.

Rear differential fluid check/drain and refill if necessary.

Inspect the brakes, shocks, suspension etc, get to know your car.

Take some photos, make notes etc.. document where you are starting from as well as the progress of your project.

I would definitely drive it for a few months to get to know what is or what is not working to your expectations before I tore into a major bunch of changes / modifications.

Make a list of the things you would like to update, replace or modify.

Lots and lots of great folks, vendors with plenty of and no shortage of smart asses too.

Welcome to the site.