Stock they are around 2100-2200 lbs.
I wouldn't go hog wild. A somewhat mild build like the GI Jane Zukiworld project is the most fun to drive in my opinion. Something with 29-30" tires, some t-case reduction, and maybe a locker or spool (or even open) in the rear. It will be pretty bullet proof and the stock engine will still be able to power it up to 65mph.
Dark Side: The stock (US) ones have a computer that control the carb and a solid state ignition, so no, not EMP proof. Besides, if a nuke goes off near your Samurai, I think you'll have bigger things to worry about than your Samurai not running.