I have just accuired an older model white sewing machine (model 658-26864) where can I find out more about it?

What more are you wanting to know about it, please? Are you sure that number is the model number and not the serial number? If you do a Google search for White Sewing Machines, there are quite a few sites that will show up in the search with information about White Sewing Machines. Here is the link: White Sewing Machine Model - Google Search

There are also links to questions on this site about White Sewing Machines at the bottom of this page. Perhaps some information that you might want to know is given on the pages of the links.

658 is the model. The rest is the serial no.

I have one too. It belonged to my father. Still works, but needs some servicing.