Thats a big board. It should be fine.
What are you asking? I'm not sure that binding settings will really help your turn initiation. Speed helps. Just go faster.
- Stance width narrow will help when you are going slow, depends on the board. Try it out.
- Gas pedal: Adjust it so it fits the boot. Pulling it out further won't help. Also most, I'd say 80% of power is transfered via the ankle strap to the bindings base to the board. The gaspedal is just for the finer feel of your edge, I never found it to actually put any pressure in the edge noticeably.
- Highback: For backside turns it helps setting them with more lean if you can't hold an edge to carve.
You could defitetely try a bit more angle in the back, like -9.
My tip, put more pressure on the front binding when riding. Like around 60 to 70%. Turn the board around the front foot. Relax - Let the board do its job, don't fight it.