Black shadow against a colored background

hi folks,

i'm trying to make a drop shadow that goes all the way around an image to
then be placed against a colored background (#fffcf9).

so far, i can't figure out how to make the shadow all the way around, and
i've just made a regular drop shadow that dips over to the right and down:

convert -page +8+8 inputpath -matte \( +clone -background black -shadow
60x4+8+8 \) +swap -background none -mosaic outputpath

i'm also making a PNG against transparency, which i'm thinking is
negatively affecting performance.  it would probably be wiser to create the
black shadow around the image against the color fffcf9, flattened, and then
place that into the PDF downstream.

i'm being daft i think, but i just can't get what i need here.  may i ask
for some help?  i really appreciate it.

- J