The correct c-body bumper bolts are 1-1/8" in diameter. Most every source selling restoration bolts are 7/8" as that is correct for A-B-E bodies.
That is a noticeable difference and can be easily seen from 5' away. Not as important, c-body is 1/2" the others are 7/16"
This is an original c-body bolt next to an original a-body bolt