Well, if you abandon the notion of fuel as the culprit (I wouldn't) and assess the electrical as the problem, you quickly run into some contradictory facts:
#1 & #4 cylinders are paired by the ignition, as are #2 & #3. So, if you were having a problem with points, condensers, or coils, then you would see the issue of cold pipes and fouled plugs/dry plugs on these paired cylinders. You are not.
With cylinders 2/4 running very rich, this is definitely a fuel problem. You are getting spark to 2/4 but it can't burn the amount of fuel. You could argue the spark isn't strong enough, but it's still not strong enough for the amount of fuel present.
And because your spark is present on one side of the coils, but not the other, this is pretty hard to declare as an electrical issue. Of course, it's possible that you have the spark plug wires wrong? Left side coil wires to both outside cylinders (1/4) and right side coil to inside cylinders 2/3). Is this how you have them?
Even when there is no fuel, the spark plug firing will warm up the pipe a little bit. So is the exhaust dead stone cold, or much, much cooler than 2-4?
And final nail in the coffin on electrical being the issue is:
"Fuel is misting out the intake side as well".
So taken in total, the evidence (I'm assuming you've got the spark plugs wired properly) is clearly fuel. start by performing a clear tube method level of your carbs. Please snap Somme pictures of each carbs level.
If you've bench synched them, they will run pretty well. Maybe not perfectly, but pretty well. Also, make sure the fuel line routing from the test tank is mostly straight downhill avoiding any loops below the fuel inlet.
And before you re-test, clean or replace the fouled plugs. Continued use of them will distort your findings.
