Given you are building in 1/72 and using brass stanchions, you have some options for replicating wire rope safety lines. In TF 72 the default option seems to be using fine brass wire, either 0.45 or 0.5 mm, then painting as you feel appropriate to replicate the look of the wire rope. Some builders solder the wire, and some tack it into place with a glue of choice. Fine fishing line can certainly be used, as can products like EZ-Line, or similar materials intended for small scale model biplane rigging. On a recent build of a 1/72 WW2 Frigate I used a YLI brand silk thread, grade 100, in a mid grey metal colour. Not sure about the longevity of this yet if you have an operating model, but I build all my rigging to be replaceable. Finally there is a Coats Dabond polyester thread, size V69 would be suitable for wire rope lines in 1/72. This is intended for marine upholstery, comes in both a light and dark grey and is UV stabilised for exterior use. This is my current favourite, though it only seems to come in big spools - 3000 metres! If you are using a line, thread or filament, then the ends of each line can be doubled back through a small sliced piece of brass or aluminium microtube and crimped. This makes it easy to tension the line when fitting, holds it securely, and it can be snipped off if you need to do it again. All of this stuff is available in Australia.