1966 Canadian built valiant custom 200 convertible

Interesting fact regarding what dana67dart mentioned about claiming "numbers matching" on a 1966 car. Should have said: year correct as it is difficult to determine as fact.
MY fender tag shows the build date was May 3,1966 as does the rad support. My block numbers shows casting date 2-17-66, However, l scraped off the paint on drivers side block below the cylinder head, shows B-273-03-02 ??
Also, there are a couple of items on my fender tag with information l cannot find?
Upper lower case letters- under "W", there is number 6, and
Middle row, upper case letter "E" , there is a number 3.
Anyone know what options these are to confirm?