what is appropriate volume of cans for milk?

Hi Hunter! Apologies for the confusion on my part :) For the condensed milk, I use a 14 oz can and for the evaporated milk, a 12 ounce can.

It looks like the Carnation brand of evaporated milk that the author recommends typically comes in a 12-ounce can; the same brand also offers a 14-ounce can of sweetened condensed milk. I hope that helps! https://www.target.com/b/carnation/-/N-56e85

Best I recall, a standard can of condensed milk is 12oz., evaporated milk 10 0z.; something like that, anyway- your store may also have some half sized cans.