On a C channel frame would boxing it or if parts were available just double up the frame rails to increase strenth and torsional strength?

boxing it is basicly impossable because of the wiring/lines/ brackets on a chevy frame but if you wrap it that will defenatly increase the strength. just remember it will also add alot of weight. and it will be costly.

its not impossible.. ive seen it done alot. relocating the items you mentioned is not hard... I am unaware of kits or plating that you can buy.. pretty much a do it your self thing.

My intention was to use a complete frame same truck and cut it apart in the middle of the rear leaf and then somewhere under the cab 3' past the bed gap and then cut the top lip off the whole thing then weld/ bolt it over the origional frame. I would have to modify the rear cab mount and front rear spring hanger as they will be in the way and now will be 1/4 in or so further outward but not that big of a deal.
I also like the idea GM has used on the newer trucks where they use a 3 or 4 in diameter tube and it punches through each frame rail and is welded all around the tube basically replacing the older riveted crossmembers. Adding a few of these will help with the torsional strength I thought as well.