I generally only use a swivel and no sinker, but depends on current flow. The leader from swivel to hook is about 300-400mm long and I use a uni knot to hold hook on, but mosquito hooks have a tiny eye, so 6lb is the biggest mono you can get through the eye, but snoozing heavier line works.
I don’t fish land based as I have a boat (you’re welcome out, but need you to tow the boat as I don’t drive - explain if you pm me). However Kingies are a lot more common than folks think and I’ve caught and seen them around most wharves and structures around Lane Cove, Gladesville, Middle Harbour, The Heads and heaps around Clifton and the Piers (Pier1, 2 etc) and around opera house and Kirribilli. My experience is they are always on the prowl and if you hold position long enough they will cruise by.
Having the bait they are feeding on is the key. Live squid or cuttlefish are their preferred food, then Slimies and then Yakkas. I’ve even caught them on swell and mado’s when they are really hungry and also caught them on bread when burleying for Yakkas (rarely ever land them on anything less than 20lb line).
Kingies like structure and current, when you get these together they will cruise past at some stage, but they can be extremely frustrating at times as they will be feeding on jelly prawns or tiny “eyes” and just will not take a bait. Other times, they will smash anything that hits the water (I caught 86 at Longie mid summer, just before aa southerly blow and had to stop fishing as my mate and I were cramping up - only kept 3 fish).
My favourite lures are white and pink 6” Sluggos and Atomis Plazos. Generally don’t have much success on hardbodies or metals.
hope this helps.
Bob