Seeing as the spokes are tired and soldered, unless you plan to spend an entire work week deconstructing the ties there is really no easy way to save them. You are probably also going to run into a nipple or two (or more…) that will most likely be seized. So plan your attack slowly and carefully.
New straight pull spokes are made in nearly every size so that’s not the issue, but for you material may be. Stainless is your only option unless you somehow find nos. In witch case what will you gain in the end?
Who doesn’t love wheels and the plethora of choices they come with!??