Some sources claim that these formats were supported in previous versions of Microsoft Office (2007 and older) and so if you have access to them you can be successful with wks to pdf conversion. Microsoft Excel 2010 and later cannot open or work with WKS spreadsheets, regardless if they come from Microsoft Works or old Lotus 1-2-3.
Open source programs from the Libre Office and OpenOffice bundles still support WKS format and can be used to successfully convert WKS to PDF. Corel Quattro Pro supposedly also still have support for WKS format.