Those R45's are typically one stage hotter than what the default or factory plug that came with the motor would have been. Going hotter is one way to try and compensate for a lot of short distance driving and/or idling.
Agree about the fuel filter. +100 on using a metal canister filter. The glass ones are cute and dressy but dangerous in a closed environment like an engine bay.
Curious about all the RED wires running all over the landscape. Someone attempt a rewire or repair and only have red in the drawer? And the one pic shows a red wire wearing a serious ball of black electrical tape. Hope whatever is inside the cocoon is not two wires just twisted together and mummified.
Solidly agree about the carburetor. It needs to be returned to it's default or as delivered settings for idle stop and idle mixture.
Rubber dry rots. Even under the hood, heat and oil and U-V exposure and kill your hoses. It might not be visible as tears and splits but damage can still be present. if the injured line is a vacuum line then it tends to collapse because it can't resist the suction being applied to it. The good news is that those hoses can be bought as a bulk item off a bobbin or spool and paid for by the foot.
7.0 to 7.5 lbs fuel pressure to the carb? Yeah, you could actually be overwhelming the floats and needles in the carb fuel bowls and gas is pushing past them and into the venturis. Might be a thought to give some consideration to pulling that pump and finding one with a lower delivery rating. Possible that a previous owner thought that the Edelbrock, being a high performance carb, needed a stronger pump to match. I could see the necessary if you were running a Dominator or tunnel ram and two fours but for a skinny 650 cfm single four barrel, Nah.
With the motor running and at idle, if you whack the accelerator at the carb to bring the rpms up, you are still only operating the primaries. The secondaries don't come into operation until close to wide open throttle such as when you are passing another car or on the strip and launching at full throttle against a tree or main street traffic light. (NOT RECOMMENDED!!!!!) Not seeing any activity from them when at idle is normal.
And the passing comment about keeping a diary or log book in which you record all the changes or adjustments you make and in what direction is not a bad idea, particularly if, as has been suggested, you are now in the middle of a multiple issue situation. Recording how many full turns or half turns or quarter turns or less than quarter or ??? can seem to be tedious and reasonless but using Nascar as just one example, for every track and many different conditions, all the teams have setup books that they have compiled based on multiple visits over time. Every twist of a screwdriver or turn of a wrench or input change made to a ECU is recorded and the consequences tested and noted. The generic term here is TUNING which is just about where you are in terms of getting your engine to cooperate.
Nick