Darrell, in other words, you're saying that the South American factories could no longer build a Y-block with stacked intake ports after 1964, but they could come up with a modified Windsor-based head to replace it? That doesn't make sense. 

To make some sense of what took place, it’s easier to put this in a chronological timeline.  Ford cast 292 and 312 blocks for U.S. production until the end of 1967.  Those were used for warranty, service replacement, industrial, marine applications, and over-the-counter sales.  Up until 1969, Argentina was using the original Y design for their own applications.  Comes 1969, the SBF head was adapted for use on the Y block as it was narrower than the stacked port design and was a better fit for the narrower engine bay in their next generation Fairlanes also being introduced in 1969.   At this point in time, the new design was designated as Phase II making the original design Phase I.  It must be noted that the original FYB stacked port cylinder heads were much more complicated to cast than the SBF head design so that likely helped in the decision to retool a new head for the Argentina Y-Block.

Lorena, Texas (South of Waco)

thats not what i said.they build both heads for years.they used the same car body style for years.same as brazil and others they didnt make enough cars to change every second yearsame as engines

This TECH ARTICLE may help to explain the reason(s) -

https://www.curbsideclassic.com/cc-global/cc-global-ford-argentina-fairlane-with-292-v8-the-y-block-gets-a-high-performance-second-act-in-argentina/

https://www.fordbarn.com/forum/showthread.php?t=287906

____________________________