Will 56" rear springs work on the rear of a 71swb

[coggonobrien]

Just trying to decide what springs to purchase for my 4x4 conversion. I'm going to go with the 52" front conversion using DIY4x hardware. Should I go with 52's on the rear as well or can I use 56's? The most offroading the truck will see is driving through corn fields or bucking snow drifts down the gravel. I do plan to have the ability to pull our 24ft tiltbed with vehicles on it. The rest of the truck consists of a fuel injected 396, monster 700r4, np 205, and a dana44/60 combo from an 84 dodge 3/4.

Thanks for the advice.
David