Did tomato paste come in only one size of can in the 1950s?
From: http://www.ellenskitchen.com/pantry/cansize.html


  Can sizes change over time, important if you are adapting an older
  recipe. Prior to 1980's), #303 was the popular size for most fruits
  and vegetables.;
  
  No. 303 = 16-17 oz.(1 lb.-1 lb.-1 oz.) = 2 cups = 4 servings;     
  
  Principal size for fruits and vegetables.  Also some meat products,
  ready-to-serve soups, specialties.


Tomato paste has, as far as I know, always come in size 1/2 (6 ounce) cans, at least since I began using it, starting in the mid 1960s.

Think this is what you are looking for.

There are lots of information bits on line, search; 'can sizes'.

cheers