1964 plymouth valiant with willwood B body breaks

1962-1974 Mopar B & E-Body Spindles

This fits within the years you mentioned. Wouldnt these work ?

Those are the 73+ spindles. They will fit B/E bodies from ‘62-‘74, but that Wilwood brake kit you listed will not fit those spindles. That kit fits OE spindles used only from ‘70-‘72, which use a different wheel bearing than the ‘73 spindles.