I have a 95 dodge 2 wheel drive dump w/ 8 ft. western.you need lot,s of weight and good tires this truck works with a 99 Q cab 4x4. The dump does big open flat lots NO docks NO hills You will need big battery.high output alt. & TRANS COOLER is a must.
Grade - I plow with a 2wd GMC dually myself, everything allabout says is true. You can do it, just make sure that what you have in mind for the truck is within it's limits.
One other consideration may be the plow mount. I custom built everything for mine, I'm not sure if anything is readily available to bolt right onto your '86. There may be a bit of custom fab work required.
Going with a 4x4 is the more expensive way to go, but depending on the sort of plowing you have in mind it may be the best decision. One thing to keep in mind is: Will the 4x4 be able to make money for you when it isn't "snow season"?
In my case, I put the plow on my 2wd because I know several places that use 2wd 1 tons for plowing and they work fine for them, I had the truck already and I weld/custom fab for a living: making my own mounts was no problem at all.