Your jeep four banger is not lazy, it is just a four cylinder. It was never designed for huge tires and the multiple suspension changes that are done today. It was designed to move the jeep from point A to point B. If you need more "power" the cheapest thing to do is to regear to 4.88. This will allow you to feel like you are moving again. If you want to do the swap to the inline six, it is more than you realize. If you have a donor vehicle, great. But it is a lot of work if you have never worked on vehicles before.
You may want to look up NOVAK JEEP CONVERSIONS on the internet. They have all kinds of information for you about jeep conversions.
Please don't misunderstand me, I am not trying to dissuade you from this project. I have put a Chevy V6 in my YJ because I owned the V6 and an inline jeep is too long an engine in the engine compartment. Yes, it fits but working on it is a pain. A V6 engine fits so beautifully and has so much room to work on it, but again, if you have a donor vehicle then its a moot point. I have over thirty years working on vehicles, old and new. I am still learning but that is a lot of experience in the mechanical field... tinkering to full blown rebuilds. What you want to do can be done by you, if you take your time and don't rush it. Some jeepers just slap it together and that is it. When it blows apart a few months down the line, they ***** and whine "why did it happen?" Take your time, take plenty of digital photos with a real digital camera, not your cell phone and store them on your computer. They will help you put it all back together BECAUSE YOU WILL FORGET HOW SOME OF IT GOES TOGETHER. Be patient and do it right and your vehicle should last the next 100,000 miles.
Check out "YJ V6 Conversion" if you want to see a frame up restoration of my 1992 YJ.
Check out "WWII Jeep Photos AND Restoration of..." if you want to see the original JEEP in action...