Well, finally crossed one off the list...

[Bruce_in_Oz]

There is a jpg scan of the old instructional charts for these carbines floating around the Net, and probably to be found on a link very near this one.

No dimensions for the location of these screws is apparent, but they appear to be located longitudinally, halfway along the rear sight bed and about half way between the top and bottom of the fore-end at that point. See photo 1 above, for the general idea.