Bad running 318

That looks like a heated-water intake.A carbheater.Seen it on a Ford once.It works similarly to the exhaust crossover.
Your problems are more than one.
-The hard hot-start could be fuel percolation.Are you running the correct fuel?
-The crappy cold running? thats a toughie.Sounds lean. Does that carb have an adjustable metering rod system?If yes crank them up a bit.
-Also make sure the initial timing is generous, and that the vacuum advance can is working.
-Whats a shunt truck? What year is it?