I ran OME 850/863 springs with heavy shocks on my 92 80 series, and really liked it. I kept the stock gearing with 31x10.5R15s. While in the states, and in Flagstaff, my DD mileage was 10-12mpg. In Mexico, fully loaded, I'd routinely see 15mpg, given the lower speeds.
The OME springs gave me...