Is there a good Duroc boar that can add some width in the front leg area?

There are lots of good red boars that will do what you want. I would try these studs, call them and they can match up the best boar they have for your sow:

Crossroads
https://crossroadsgenetics.com/sire-sta ... ent-sires/

Chad Hill
https://www.chadhilldurocs.com/new_boar_page.html

A Cut Above
http://www.acutabovesires.com/sires.html