I'm with Rumrumm on this one. My plan would be boxing the rails on the existing frame, then fabbing up the necessary mount points to use the transfer case, differentials, and suspension out of a donor truck. Haven't seen many bolt-the-body-on-a-newer-frame deals that come out looking right. Usually the track width is wrong and or the wheelbase is wrong and most tend to "comprimise" on the dimensions and the truck ends up looking tacky.

Got a sign in my garage that sez, "If you don't have the time and the money to do it right, when are you going to have the time and the money to do it over?". It's there as a constant reminder to me to avoid the quickie shortcut deals that always seem to cause way more problems then they ever cure!!!!!