you have two different stamps going on there. It seems that your reference stamp a #220 and
the ones on cover could one of a few different options depending on what type it is. Need a larger and more clear image of them to see the triangles, Georges hair and possibly toga button. Nice looking cover though!
Edit:I noticed it has a #279 Postal Union color
green 1¢ Franklin so it most likely is either a
#279B or from how the color of them show up on my monitor -kind of an
orang-ish then maybe a
#279Bd. look to see if they are Type IV's.
(I see in the title it says they are Type IV.'s)
Use these to help you determine what type they are if you aren't sure?
-Cheers

