I'm going to almost totally disagree with RR on this one.
This is where to start, and I'm very serious. Don't worry about those other Edelbrock threads. Some may be relevant, most won't be.

1. A notebook if you haven't already. Because it is too much detail to keep track of in your head.
This I'm pretty sure I got the timing right isn't very helpful to the rest of us. Being "pretty sure" and "right" is open to too much guessing - What some people think is right, others think is wrong. Post the numbers. What will work best and what your goals are will depend on mods (in your case apparently none except carb) and whether you're going for stock timing setup with emmissions or hot rodded to some degree (considering its a stock engine).

1a. This occasionally will backfire thru the carb is timing related. It's firing early, before the intake valve closes. Write down the timing at rpm from idle until it stops increasing. (Plug the vacuum advance line for this. Golf tee works well.)

2. Download the Edelbrock Performer and Thunder Series Carb Owners Manual.
a. Notice on page 2 that the idle fuel is controlled by 2 restrictions, 2 airbleeds, and idle mix screws. ( Not the rods and main jet.)
b. Robert is correct that fuel level is important to be set correctly because the weight of the fuel in the bowl adds to the atmospheric pressure.
c. Chrysler's Master Technician series has some decent booklets and filmstrips on how carbs works (and they tend to focus more on the Carter designs). Check 'em out. Look under 1966 and '69.
http://www.imperialclub.org/Repair/Lit/Master/index.htm
http://www.imperialclub.org/Repair/Lit/Films/index.html

3. Vacuum advance connected to constant vacuum. Well... whether this is best way to do it will depend on your goals.
Stock factory setup will require everything to be like factory at the starting point. That means idle stop solenoid if applicable, factory initial timing, and ported or manifold vacuum - whichever the factory used.

But if you are going for a more typical hot rodded set up, no idle stop solenoid, no egr, then whether ported or vacuum source is better will depend on the initial idle timing you use as a base. Your cam should pull good vacuum at idle, 12-15 in Hg. That's more than most hot rod or race cams, so your using manifold vacuum will add significant timing at idle. Having lots of initial mechanical plus full vacuum advance at idle can result in will run best with a very lean idle mix, but likely too lean to have good power when you let the clutch out. It's a balancing act to find what the engine wants.

Start with timing as discussed and then idle mix. If there's any issues with the idle and low speed drivability that can't be adjusted with the mix screws and throttle position, then look at the fixed restrictions. You'll have to the measure the restriction sizes using shanks of small drill bits (or gages if you have access to them).

Once you have idle and low speed driveability, then work mid speed and high speed cruise. After that, tune the accelerator pump to cover and work on high speed WOT tuning. The chart in the Edelbrock book will be a big help on the high speed (interstate highway) and WOT tuning.