I use 40lb nylon coated wire, but also have 100lb-ish Sure weld. I just do not like the colour of the sure-weld, probably would use it only for Night fishing.
When my 40lb runs out I would probably buy 60 or 80lb to replace it. I now use wire trace for all of my surfcasting.
All of the commercial ‘pre-made’ shark rigs use very heavy duty wire.
edit: Do you trust the melting feature of the Sure-Weld?, I just crimp mine.