The 5.9 is a monster, my cherokee will spin all 4 tires on dry pavement...of course it gets 4 gallons per mile, and yes, I know I typed gallons per mile. I don't think you'll fit the 4.0 in there without a LOT of work...the 5.2 really would be a better option.

98 Grand Cherokee 5.9 (Using 10% of the nations gas daily)
95 F-250 (The other 90% of the gas)
95 Honda Del Sol V-tec (Corner Carver)