I'd guess that Canadian GMC said GMC on the valve cover even if they had Chevy engines. How about K'nucks?
And you would guess wrong! If it has the script it would be an American GMC motor, and should be a 270 for the 57 model year. The script changed over the years, as did the location of oil fill holes or breathers, but the 228 valvecovers will fit a 302 and everything in between.
