318 REBUILD IN 67 BARRACUDA

I don't believe that anyone would want to remove the exhaust manifold butterfly valve if they were going to keep single exhaust. That valve is supposed to reduce backpressure from the other side, so it needs to be kept loose and able to move freely.
You should also consider what type of choke you are going to use, e.g. the one that needs the exhaust heat applied to the intake manifold choke spring or electric or manual. Maybe the LD4B intake manifold doesn't have the heat pot in it, I don't know.
If you are going to use electric or manual, you really don't need the intake manifold to be heated unless you live in a cold climate. An electric choke would be another thing you could use if you changed to dual exhaust.
Also consider if you want the heat crossover port in the intake manifold to be heated or not. There are intake manifold gaskets that block off that crossover port.
Richard