I don't know about all the other questions about fit but I will answer #2. There has never been a "Super Commando" 273
and all 273 manifolds are the same whether 2 or 4 barrel.
Correct in Plymouth it was called the 273 “commando” and in the Dodge it was called a “charger” 273. I know that they used 2 styles of driver side 273 exhaust manifolds, one is longer and snakes through the bottom a little bit more and points towards the rear, that one also has two brackets that secure that end to the engine better...The other style is a lot shorter, I’m not sure which years used them, there might be a commando style exhaust manifold for the driver side but the passenger side was the same and both had the same size exhaust ports.
