69 Dart / 70 ^ 318 Which Upgrade Kit for Factory Air. Lil Help Here Please

Nice Dart ! As with any kit you will find you will need extra parts.
The 70-74 kit #23-301-SB is the right one for 318's with the aluminum water pump.
You Car has the right radiator and upper hose to clear the compressor.
You may or may not need to run the 2 belt set up for the compressor. I only run 1 belt on mine.
Be ready to shim/adjust/align to have the belts running true.
I noticed your alternator belt is mis-aligned right now.
I just installed Vintage Air in a 318 B body.