Always leave the vacuum advance tuning for last, the vaccum advance is the fine tune knob on the engine, you want to make sure runing on mechanical things are working right.
I always keep my Allen key in my console to compensate for bad gas or if I make a change when driving. Just like white I spent weeks driving the car and adjusting for ping until I got it right on ragged edge.
You start with the advance fully on, clockwise all the way. Then you back off till ping stops, if you have to go fully counter clockwise to stop ping then drop mechanical initial timing 1-2 degrees and start again. Usually you back off 2 full turns at a time till ping stops then you come back up 1/2 turn till it starts so you know the limit.
Then I like to back off 1-2 turns to have a safety zone for sitting in traffic when its 100 outside. Then you drive it and see how you did. Took me a week of driving season to dial it in just right.
Exhaust pipes make a huge difference due to back pressure. Back pressure causes a double dip of fuel from the carb so a smaller exhaust besides holding an engine back also riches the intake mixture.
All the bends in exhaust pipes cause different levels of reverb and back pressure that quiets a motor and also keeps the cylinders from pinging. You can have an engine that breaths and farts too easy and it basically sucks the gas through the motor so fast that she runs leans.
The exhaust can also effect timing when you add headers it has the effect of retarding timing this is because of higher flow and heat loss. Those big heavy stock exhaust manifolds actually do a job of holding heat inside the cylinders keeping them at proper temps for combustion and the design bounces air back into the engine helping the double dip signal from the carb.
Ford designed this weirdness into the exhaust ports and the intake ports on the Cleveland that is why the ports don't line up, so the big mistake when people port and polish is they take out this misalignment in the exhaust and intake manifolds.
Yes you are tring to run more mixture through the motor faster to make more horsepower but it causing horrible tuning issues for a street car that has to drive under 2500 Rpms. On a drag car launching over 2000 its good but not for a street car.
Had a buddy running a 3" exhaust for years he had nothing but problems with runing lean and detonation. I told him change the flange on the collectors go down to a 2.5" and cause a restriction after the headers. He didnt believe me but tried it instantly the engine richen end up from back pressure and carb double dip and he could finally tune it right.
Carb double dip is caused by the back pressure wave from the exhaust you get a reverse air wave back up through the intake manifold and it signals the carb to drop more fuel so you get a richer intake charge without touching anything.
Again these are things you care about for a street car, on a drag or racing car different situation.
Hook it to manifold vac and it will be easier to adjus the advance. On my old dizzy i drove for a couple hours with that allen wrench in my mouth like a toothpick, pulling over every couple miles and adjusting the vac advance. Was concerned i was moving it too much but not getting a difference in the mid-throttle detonation. I figured a 1/4 turn would make a difference. It didnt really. I gotta think that relative pressure in the weather makes a difference. I am at sea level. I eventually backed off the adjustable vac advance around 1 1/2 turns to reduce detonation with around a 18 initial. Then i went to a MSD dizzy that doesnt have an adjust advance from the manufacturer. Had to buy one from Crane. The whole adjustable advance thing has discussed here, but a few refuse to admit the Ford had put a version on some of the high performance cars. I believe 429's had them. It was a shim style, NOT the allen screw type we have available today.