WTB: 5/16” x 1” BSW Bolts, Nuts, and Washers

I’m looking for four sets of 5/16” x 1” British Standard Whitworth (BSW) bolts, along with matching nuts and washers, for a 1964 Norton Atlas restoration. Preferably looking for vintage or period-correct hardware. Any leads or availability would be greatly appreciated. I’d be happy if they were worn and pitted. Not looking for anything new or shiny.

Thanks

This is what I’m looking for.