As it happens, I have just taken off the centre stand of my '58 GF, frame number FA7 3109
The right leg was bent, so I heated and straightened it, and just finished painting.
The distance between the frame lugs is 3 1/2"
However I don't think it's an original stand, because the stand's spring attachment is on the wrong (left) side, and the previous owner welded on another attachment on the right side. Could be, as Trev mentioned, a 1960 or later stand.
I also found, when stripping the paint, there was bright red paint underneath.
I have a feeling though my story might only ad some more confusion