Check that cowl tag build date again, probably not a A after the 8. I have one vin lower than that, and several between that one an 500100, and none of them are 08A build week tags. Don't have a single Norwood built 08A car. Maybe a pilot car? Would need to see a picture of the tag itself.
Is the number above a body number (its in that format but there is no 500000 series body numbers) or a VIN which would just be N500026?