Conventional
wisdom based on the practicality that the emission devices are no longer on your car is:
1. Distributer advance- from front carb, port closest to valve cover. Distributer retard is not used.
2. The rest are all capped to include the egr ports on the manifold. Check this to make sure they are tight since various methods have been used- a real metal cap, crimped and soldered egr tubing, etc. I've found leaks there.
3. Optional- tie the carbs together. Simple- the two ports closest to the fender. This assumes you've tuned each carb by a vacuum guage. The theory is that multiple carb installs benefit from a steady ( constant) source or that manifold pulses are optimized, or if one bank of cylinders is slightly different it balances out the equation. Works for some, not for others.
4. I didn't try this, but will next time I do a major tune- the two manifolds tied together if T'd might improve the vac signal to the distributer.
Here's the original EGR/ VAC setup for most as there were several including a CA only version w/ air pump and fuel return line: