Originally Posted by mb power wagon
if you go with the original hemi (426 big block) the first thing you should take a look at is whether the frame your gonna use will handle the torque of it. in alot of cases an added cross member or if the frame your using is a "c" channel style just boxing in the frame will make a huge difference in strength. thats part of the reason all the new power wagons have fully boxed in frames. it also helps with the chassis twist of hard off roading. as for an engine i'd probably rather go with the 383 magnum. it's not the 426 hemi but it's a stump puller of an engine and has the possibility to make more torque if it's done right. keep us posted what you decide and pics of the build i wanna see this beast.
An 'original hemi' would be a 50's Chrysler/Dodge/DeSoto engine. The hemis the OP is looking at are variations on the new 3rd gen hemi.