The 216s all had the the "tall" sideplate cover on the pushrod side of the engine.
Canadian 216's had a short side cover in 1951 and possibly earlier. I have never had luck finding Canadian 216 block casting numbers anywhere but the casting numbers for Canadian 261's show up in the listings.
More importantly you want to determine if it is splash oiled or not and a sure indicator is a small plate bolted to the driver's side of the block called an "oil distributor". There's a picture of the splash oiling system on this page:
http://chevy.oldcarmanualproject.com/shop/1948_51truck/51ctsm0605.htmIf there is no plate there then your truck has had a later, full presure replacement engine installed.