It looks like you are talking about a border strip 3 1/2" wide by 52 1/3" long. I usually go for the whole piece. If you must seam it, use a diagonal seam since that will fade into the background more easily. (I just did a pillow case with 2 borders and one of the pieces was about 4" WOF narrower than the body and the other border -- I did a diagonal seam and it hardly shows. I have done this on regular borders too.)