Most trailers are 750 to 1200 pounds, depending on size and matierial etc. Instead of messing with the front spindles from a pickup, you can hae a decent 3500 pound axle from Northern Tools for $269 that includes springs, shackles and hubs. Just add wheels and you're set.
You can part out the Ford and come away with the money to buy the axle and parts. In the long run it would be better then trying to cobble together a trailer.