Gear ratio with 38.5x11x16 Swampers

I'm looking to throw some 38.5 inch Boggers on my 1981 Suburban.  I'm sort of new to the off road world, got the bug, bought a rig, started a build and now my wife doesn't understand me.  Anyway, I'm looking for advice as to what gear ratio I should go to with these tires.  My rig runs a 454, bored out 30 over with the 700r4 transmission and a 6 inch lift.  The only time it will be driven on the street is traveling back and forth to the fire house, which is a 16 mile round trip on a back road.  I'm aware that I'll have to do some trimming here and there, which is all good.  The thing is, my suburban is a dually.  I bought it from a guy in Idaho who used it to pull his horse trailers.  Any advice from you veterans is greatly appreciated, thanks.