I have been quietly looking for any pre-war "AS" heads for years and haven't found anything. Be aware that Ford did make aluminum versions of "AS" heads. Kube has a nice thread about restoring a 1940 Ford convertible factory ordered with aluminum 19AS heads. My memory is these were made pre-war only. I think it was Bruce Lancaster who wrote about a post-war (1946) Ford bulletin trying to sell the remaining stock of "AS" heads on their parts shelves.
edit: here is Kube's thread I mentioned:
https://fordbarn.com/forum/showthrea...7264&showall=1