Don't use the trailer springs... They are wider yes but not the same height when slung... the arse of the truck will always sag down making the truck sit goofy looking. In order to keep that from happening you will have to add about 2.5 inches of spacer blocks between the frame and hangers, which is a PAIN in the ARSE and dumb looking to boot... (IMHO)
Hunt down and find a set of front springs to do the job, in the end you will be much happier. They are also easier to hang and get straight as you have the front of the truck to go off of... That makes a big difference in set up time.
Planning your build is up to your personal choice on how to do the job... When I did mine, I'd say it was about a 18 hour job working by myself but that included going through the whole rear end, brakes, wheel bearings, flipping hubs, etc... Had it not been for all of the extra it proably could have been done in about 12 hours.
http://www.steelsoldiers.com/index....ays=0&postorder=asc&highlight=diablo&start=80
Things to consider while your poking around back there are... u joints, seals, wheel bearings, new brake lines, wheel cylinders or kits, new rear harness (much easier to cut down than the old one). Most of the part numbers I used for the job are posted in the parts X section so they can be had locally if you want / need them.