Have not tried to re coil with a dual coil so can't help there. But i have been rebuilding the heads with a single coil 5 wraps of 30G with 2X 3mm silica wicks laid one on top of the other, comes out right around 1 ohm. I normally
vape quite high VG
juice and have been getting really good results with this config. I find any less silica and it floods straight away. HTH