69 valiant carburetor 1920 Holley

When it comes to making adjustments, and tune up, you will need a timing light and a tachometer.
You might find a light and tach/dwell for nothing or next to nothing because its been collecting dust in someone's basement for the last 20 years.
But regardless you need both.

Before making any adjustment see if the carb and distributor have been changed, and if so, are they the exact version for 1969.
The factory distributor and carbs for 1968, 69, 70 etc need to work together for the factory settings to make sense.
If one or both have been changed, then might have to use pre-CAP settings. Right now assuming the car has its original carb and dist