If you're determined to butcher up an otherwise pretty serviceable truck, pick the 56. It would be possible to swap the sheet metal onto an S-10 frame of the right year and wheelbase, and leave the running gear intact for someone to purchase who appreciates old iron in its original form. The S-10 will have independent suspension, disc brakes, and the right mounting points for just about any hotrod setup you choose, except maybe some sort of big block installation.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!