Getting psyched to start my 68

[hardliquor1]

I've been following off and on for the past few years and am ready to take my 68 c10 swb into complete restoration. I have a few questions regarding the best place to shop for suspension parts and disc brake conversion. I am going with a 4.5/ 6" drop, will have to notch the frame in the back, change the cross member out and I also need to box the frame for the 496 700r4 (stroked 454 with Brodix top end) BBC that is complete and ready to drop in with the exception of the headers I have to have custom built. Has anyone boxed their frame? if so, where and is there a kit available that I can weld in?
I am replacing everything with new or better than stock components. Any help, advice or direction is appreciated.