Shoe box Fords with stock frames are not good candidates for Mustang II suspensions. That is why the major manufacturers do not offer crossmember kits. Fatman Fabrications offers a "clip" with a crossmember for your application. http://www.fatmanfab.com/06page6.htm

Junk yard crossmembers and components should be approached with care. $200 or $600, it makes no difference. You will need to rebuild or replace all of the components that wear to include the rack. Ford stopped selling replacement crossmembers because they had reservations about there use when cut away from the unit body.

Your stock front suspension is not that bad. There are companies that can supply you with dropped spindles and disc brake conversions. Look into rebuilding and upgrading what you have.