You would get way more power out of a semi built 350 than a supercharged 4.0... Depending on the year the 4.0 has about 190 hp max, but a good deal of torque. And a 4.7 swap would be doable but incredibly hard. Burnville offroad, a local 4x4 shop made a 4.7 TJ, but they said it was a tough swap, and they've done a Viper V10 TJ, so if they think the 4.7 swap is tough, it has to be
I own two Jeeps, one with the 4.0 and one with the 4.7. The 4.7 is a nice motor for a stock car, but would definetly not be worth all the time/hassle of swaping one in, and don't get me started on the 4.0... its a great motor for offroad, but is a severe dog. Also, the supercharger available for the 4.0 is from Accurate Power I believe, and while they look like a good company, the one guy I have heard of buying stuff from them: 4.6L stroker kit for his 4.0, has gotten the real runaround now that his motor they built him burns a quart of oil every 1000 miles or so after the rebuild. They claim this is normal with under 10k miles on the motor... uh huh, so I would not really trust their customer service. SBC is probably going to be your best bet cost and ease wise, as there is a kit to swap a 350 into just about anything, and if you get a 1987+ block there are performance parts out the wazoo for them. Not that there aren't for the 1986 and older, but it's just a little more work to make it all work with the emissions systems etc.