just remember that there are differences in the silver calipers too - i.e. Tokico casting - there is usually a number cast beside the Tokico. The sandcast ones I have seen up to 5528 (which Im restoring now) have always been '1'.
The rear plate of the caliper also has a longer centre cooling fin than the later K0 silver calipers. there also knurled allen bolts which are an early sandcast feature, but these would be smooth for the number you are restoring.
did I miss anything guys?