Hi Andy,
Firstly, the ammeter and ignition/lighting switch should be fitted with a rubber sleeve so that they are a push fit in the headlamp fairing. These sleeves are not listed in the spare parts book. I made mine by cutting about 5/8" from the top and bottom of an old fork gaiter. The sleeves are just 5/8" of tube with an outer lip around the top (so that they dont push right through into the fairing).
The coil is suspended below the lower frame top tube - there is a shaped rubber block between it and the frame tube, and then retained by a steel strap. The rectifier was bolted to the vertical bracket under the front of the same frame tube (most owners have changed from the inefficient old rectifier to a modern solid state unit). The tank bracket you mentioned also provided the mounting for the horn. On my Dragonfly, I have re-made the tank bracket, in aluminium, to more generous dimensions so that it doubles as a heat sink and mounting for the solid state rectifier, as well as being the mount for the horn.
Hope this helps,
Regards,
Eddie.