NOOB with a TIMING light gun

This seems way too complicated, there is certainly more than one way to do everything. I am by no means an expert, so I am always on the lookout for opportunities to enhance my knowledge.

RRR you could be on to something here, the factory recommended initial setting for a stock 1973 (Electronic Ignition) 440 of 7.5 +/- 2.5 degrees BTDC, should / could have been actually 18.

If his ignition is in good operating condition, I'd wager that after he sets the total advance, that his initial would probably wind up at or near the 8 degree mark. Most stock Chrysler ignitions of that era probably have an advance of approximately 24 +/- a degree or two anyway. Of course there is no way to tell unless you have a baseline and you know the total mechanical advance, or you have a sun or similar distributor machine that can verify the advance and curve outside of the vehicle.

There is no doubt that some fine tuning or other adjustment adjustments can yield some better results after the baseline has been established and it may run best at 10, 12, 13 or even 18.

When we were really into this stuff we we bought our motors from Rod Hall in Reno and took our distributors over to the little Mallory shop in Carson City NV.
Guess what they did? Spun them up and checked the total advance, then adjusted the curve, and based on what our engine combo/application was, limited the total mechanical advance if necessary. Some of our distributors were pegged at 34, 38 or whatever worked best, that's right timed at 34 degrees all the time.

A street motor will benefit from a vacuum advance. This will add some additional advance during part throttle cruise and light acceleration but:
No vacuum advance at idle, if you are using the correct port on the carburetor.
No vacuum advance at wide open throttle.

The vacuum advance system is really intended for emissions control, drive-ability, and fuel economy.So during part throttle, you may see initial plus additional advance. The result may even be 48, 52 or even 56 degrees. But it does not add any additional advance during low vacuum (full throttle) or high rpm.

I should have known better than to offer advice...