You may be confused. Low end torque is as necessary in the desert as it is in the woods.
The 8 valve 1600 will make descent amounts of torque and better spool over a 1300 in stock format. A nice mid range cam, 2" exhaust system, the Corolla 1600 carb Or the my side 40mm conversion and proper tire size for your gearing, and you should be good to go.
Don't overlook the little things like, plug wires ( I run 9mm wires ), Good plugs,
Valve timing, Ignition timing, etc.
We run my Sammy in the woods mostly, but take a trip every year to the Alvord desert
and to China hat. Trust me , without the bottom end that my mill produces. I'd be stuck out there still.
While the Samurai is a very capable off road rig. It is by no means a desert racer.
Running wide open out across the desert with Leif spring suspension will destroy your
zuke and your back......If that is your intension. I'd be researching 4 links and long travel suspension systems, as well as some pretty substantial axle upgrades........Boxcar...