..I don't think you will find "SPF numbers" on ACs if Mr. Price does end up with the company. Understand that that the "CSX" prefix does NOT belong to SAI. AC assigned the numbers, they could have just as well used the prefix "USA" or "PRINCE ALBERT" on the cars. Shelby did not assign the number or prefixes to the cars, AC did.
That SAI is currently assigning the prefix to cars does not diminish the historical fact that the cghassis numbers were selected and assigned by AC Cars in bee-you-tif-full Thames Ditton ( you have to have been there)
Rick