I'm in the process of doing the same thing that you are, except that I installed a 3" drop axle. I went and talked to a local well know chassie and street rod builder about boxing my frame for my 350 and he told me NO unless you are going to put over 400hp in that truck. I have a 350 crate motor and th350 tranny so I'm no where near that hp. I have not installed the engine or tranny as of yet but I have new stock front leaf springs, new shocks,new shackles, new spring eye bolts and new king pins along with new engine and tranny mounts installed. I just ordered the full 5 on 4 3/4 disc break conversion kit from CPP. The entire time I have been working on this project I have asked people with the same truck and the street rod builder that I know and everyone has said that this set up is fine, but I have been told that I'm nuts for leaving the straight axle in this truck. I'm trying to keep it as stock looking as possible but more reliabile.
