New Inter forestay

[Stillraining]

Needing input on sizing for an inter fore stay on my 41 Ketch..displacement 30000

Mast and deck hardware already there..What size wire should I use...is 9/32 to small? ( have a line on a hyfield in that size is why I ask )

I want it stout enough to easly withstand 60 knots with my 100 squar foot storm jib hoisted..also will need new running backs..should I go wire or dyneema?