The assembly manual will show you how they are supposed to be placed however, I have observed many unrestored Novas 69 and 70 and the decals were NOT placed like shown in the manual. I think it just depended on who was working the line that particular day...
This is my 70 L78. The original stickers were found in this placement pattern. The spare tire being upper right and lower left being the posi decal. I have also seen this placement on unmolested, unrestored 69s... One of which being in the 1969 Hot Rod Magazine article "13 second grocery getter". There is a picture of the trunk open on that car that shows this placement also. I don't have the article handy..
This picture is of Tom Williams' 70 L78 black Nova unrestored. Notice the opposite side placement.
Hope this helps.... Rich