The previous owner (builder's grandson) believed this engine to have been started in the mid-1960's and finished late-1960's... I have Cole's catalogs dating back to 1931 and the first mention/price list I can find of the 2" is in Catalog #22, dated 1974. It is not listed in Catalog #21, dated 1970.
Here is 1974's price list and the earliest I can find the model:
And check out how much prices increased over ten years in 1984 (Catalog #24):
The 1" however is listed at least as far back as 1952 in Catalog #14, and is also featured on the cover that year. I do not have any catalogs between the range of 1936-1952...