The posts by Frizzle Fry in this thread has info on relocating the rear shocks using the stock brackets, but flipped side to side. I've done it this way on two trucks so far and it makes a huge difference in how they ride and drive. I'm about to do it on my new '66 too.
http://67-72chevytrucks.com/vboard/s...05&post4730005
I installed a front and rear sway bar on my old '66 along with relocated shocks front and rear. It had less body roll than my autocross car but rode better than my dad's completely stock '66.