Does it have the nut?? Antique screws were cut various barely different sizes, and finding a tap to cut internal threads to match, will be hard.
What size is it?
Some of them are 1/2" diameter for use in a small hand screw.
Some of them are 4" diameter for an ancient printing press, but only 8" long.
For a wooden vise, you have to discount the thickness of the moving jaw.
Then subtract the thickness of the bench leg or apron or wherever you plan to attach it.
Whatever length screw you have left is how far your vise will open.
So really, to be an effective vise screw they have to be pretty long.
2" is a good diameter. Anything bigger than that, gravy!!
yours Scott