First thing to do is find out what gears are in the axles..
The engine you choose should be able to turn the wheels. If the gears are as high as I'm thinking you may be better off renewing the v-8..
But to answer your question. All things being equal the 4.0 is a far better engine. It is much harder to get everything installed for it than the 4.2 however.
If you are still in California you better check with the state before thinking of driving on their hiways with an altered Jeep.
Big JIm <img src="/forums/images/graemlins/pfft.gif" alt="" />

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