The last chassis number for March '53 was 464 207 so beyond that it couldn't be a genuine Zwitter(unless it's on a later pan).
Looks like the car has been worked on over the years,later lights etc.
The aluminium trims for the rear windows are missing and it looks like the rubbers have been changed.The correct rubbers would be very hard to find.
Really need a month of production to really determine if the VIN is correct.