Beyond Frustrated - Wont start/stay running

No problem, previous post edited.
Bucking is, I would like to say always, a lean-running issue.
What bucking really is , is a misfire, or really; a series of misfires. As in, there was not a combustible mixture in one or more cylinders . On a six cylinder there are three cylinders that fire,per revolution; so if one goes down, you really really notice it.And even more so if the engine has other issues.
Back to lean running;
But there are many many ways of running lean.
Running lean can be not enough fuel, or it can be too much air.
Bucking while cruising is almost always lean on the low-speed circuit.

I always suspect the fuel first. If there is water in it,then,when the water goes thru the low-speed circuit, then there is not much chance any fuel in that charge will combust. Same if water gets in there from another source, like the cooling system.
The next suspect is an uncontrolled air leak somewhere between the combustion chamber and the underside of the butterflies. This could be the PCV, or the brake booster, or a gasket, or a cracked intake manifold, or anything vacuum operated that is connected to the intake.
The next suspect is exhaust valves not closing. This could be a valve adjustment issue, or valve issue or valve spring.
The next suspect is a bad intake valve allowing the piston to push some of the intake charge back up into the intake manifold on the compression stroke. Then there is nothing, or not enough, mixture left in the chamber to combust,again.
And finally we have a jumped timing chain. Now all the valves will be running out of time, probably late, and so perhaps only a tiny bit of fuel charge makes it into the chamber, and only if the butterflies are wide open, and if the ignition timing is late too, then it's hopeless. I have never had a chain go on me while driving, and have no idea how that would manifest. I don't think that's your problem.
So that's the air part. Now the fuel;
Now more likely is that the low-speed circuit is dirty. It often manifests as a bucking. If the idle air-bleeds get plugged up, then the carb delivers liquid fuel out the transfers instead of an emulsion, and the liquid fuel likes to stick to everything, and so not all of it gets to the chamber. So now the cylinder is getting the right quantity of air, but the fuel is not there. And the fuel that does make it, is not interested in burning, and so it doesn't.There's your misfire.
Now in case you don't know about emulsion;
On the low speed circuit, with the throttle valve(s) nearly closed, The fuel needs to be partially mixed with air before it ever leaves the carb. This is because liquid fuel is hard to light on fire, in the cylinder, where the air molecules are few and far between, as at cruising.
So, inside the carb is a tube; one per throttle bore. Air sits all around the outside of the tube(or is supposed to,lol).The liquid fuel travels up the tube, on it's way to the transfer port and the mixture screws. On it's way, atmospheric pressure forces the air on the outside of the tube, thru a series of little holes drilled thru the tube, and into the inside of the tube where the fuel is traveling.And so it mixes with the fuel making a frothy mixture.This frothy mess is called an emulsion. When this frothy mixture leaves the transfer port, the air passing by there further smashes it all up and mixes into a combustible mixture.
It might be compared to your wife's frappe concoction when she makes pancakes. She beats the pancake mix with an egg-beater, and makes an emulsion out of it.When the pancakes are cooked, they are all full of air bubbles.
Think of it this way; your 225/6 has a volume 225/6=37.5 cubic inches per cylinder,plus the chamber. While cruising, with the butterfly nearly closed, that cylinder might ingest only 30% of it's rated displacement. But those air molecules are spread all around the chamber, so they are very far apart. And the fuel that came in with it is trying to find oxygen to react with. And so the piston comes up and jams it all into a little space about 5 cubic inches in volume, and the oxygen molecules are still quite far apart. Now if the fuel has not been emulsified, then it tends to stick together in big drops that maybe find oxygen and maybe not. And if it finds oxygen it might still not burn.
So Emulsion is paramount for the low-speed circuit to function.