Trevor, dont use any shot on the line at all. Use a large paste float(0.75 gram) and set the rig at dead depth using a plummet and then replace it with a knob of soft paste ( halibut pelllets make great paste) moulded around a large size 10 hook. Carefully lower the paste into the swim until the the tip is just showing ( adjust depth if needed). Ignore all movements and quick dips. When you get a take it will rip the elastic out. If the paste comes off or dissolves as it should, scattering smells and particles on the bottom, the float will lie flat or the tip rise out of the water. Never use a hook length myself ,always fish straight through,as it reduces the weak links. 0.12 or 4 lbs would be OK. Your elastic set up is fine.
The key to paste fishing is not to make the paste too stiff and to get into a feeding rythmn-20 pellets every 30 secs and you'll have to lash yourself to a tree to stop them dragging you in! Good luck.