I'd be tempted to stay with the 4.11 gears. Yes generally 4.56s and 36"/37" tires are a good match, however your transmission has a nice creeper gear to get you thru places that need low speed, and the 37s will help with engine speed (and MPG) on longer trips. That 454 should have all the torque needed to move the beast anyways even if the gears ain't quite "right".
Awesome truck, I've been keeping my eye out for a crew cab 4x4 square body forever... they are unicorns.
That is an awesome crew cab and a survivor too! Most of those trucks were rode hard and put away wet, just to rust away in the back 40. That is a score and a half for an expedition vehicle! Would make an awesome flat bed!
... please keep posting wih LOTS OF PICS!
Nice truck, would love some more photos of it. Looks alot like mine.View attachment 317534View attachment 317535View attachment 317537
some inspiration for ya, my dream truck I built up in google sketchup: