1. May not be a 59 clip
2. Don't know what "won't line up means". Very vague.
3. The way it reads is you bought a truck with the splash guard in the bed. Don't know if this truck had a hood and grille or not. You bought a front clip (which can mean many things to many people) that included a hood and a grille. You used the hood and grille from the clip and installed the splash guard/valance that was in the bed and something does not line up but sometimes it does.
4. Since we can't see it or visualize it or know what is not lining up where, more detailed info would help.
5. Suggest you look at, and take many pictures of, a 59 front end. All angles and all views and then compare to see what is missing, bent, wrong part, flipped. Any previous owner could have used some part from something else and made it "work".
6. Wrong bumper brackets, rear brackets instead of front brackets.
7. Possibly 55-57 front parts are different in that area than 58-59.
8. You have double flipped parts and keep double flipping out of sync.
9. I will post pics of my 58 in a moment.