I'd plan well ahead if you intend to Bob, before you start yanking stuff off and cutting. The length of the driveshaft is typically going to determine the length/ placement of your rear springs/mounts for starters, however, it can be longer or shorter by shortening the driveshaft or also lengthening it (a job for pro's) (the driveshaft) thus you end up with your desired frame length. The rivits are fierce pieces to remove, usually a torch and air hammer(Large hammer) or a drift and sledge hammer. Also theres the jackstands and such to hold the frame/body at the desired heigth so you can do all this, and an engine hoist is handy, or A-frame hoist. All in all its relativly easy enough if your any kind of gearhead, and can fabricate or desighn and have access to a welder or a (Welder person). But take a day or two to plan your attack and all the bits that that attack will change.ie. brake lines, spare mount, rear fenders, what bed, stuff like that. There are hords of Bobbers here on SS, so as its been said a patrillion times "Do a search" and if you get stumped , ask here on the forum in a post or PM any of us, I'm sure there are lots of guys/gals here at your service.