As I look at photos of the Portu, Cuban, and Sudanese AR-10s, I think I see an A2-sized, and not an A1-sized buttstock. Obviously, with some (even reproductions) having been made out of wood, it's difficult to tell, and certainly non-standard in relation the AR-counterpart, so the terminology of 'A1' and 'A2' when it comes to buttstock sizes even breaks down, but if they had to be closest to one size or the other, can someone chime-in and say what size buttstock they have?

First let me say that if you study ARs you accept that the original AR10 is ergonomically perfect and hence the AR15 is a crime against nature. The length of an original AR10 stock is the same length as a non A2 AR15 unit but in an effort to 'fix' the crime the A2 stock was lengthened to return the ar15 to the original shoulder lop. The A2 differs from the original stock length by the difference in length between the AR10 and ar15 lower receivers ~.6in, unfortunately this does nothing to correct the ghastly trigger lop. The A2 was a return to other AR10 features like round HGs,  heavier barrel, and a drum rear sight further proving the superior design elements of the AR10.

Well that's a ringing endorsement of the AR10

And so if I read your response correctly, the original AR10s bore A1-sized stocks then?