This block appears to have plate number 8163. Odd, because the only Scott number that has been assigned to plate number 8163 is SC #501 3 cent Type 1 Perf 11.
The stamps do appear to be Type 1 but are obviously imperf; making it a SC #483.
I thought perhaps one or more of the plate numbers is incomplete (i.e. a 3 is really an 8), but I cannot match any of the known #483 plate numbers.
Anyone have any ideas on this block?