a better Woody engine?

Well, unfortunately I usually stay factory on these, but I am an auto tech so here is my professional 2 cents of advise. Give up on the MPG, or you have to basically replace the entire drivetrain as none were ever fuel injected and they all had the same engine. Even changing the engine to another carbureted V8 wont help MPG by much. The original drivetrain usually gives you about 10-12 city and 12-13 hwy. and the simple reasons for this are, heavy and not aerodynamic (not razor shaped lol), they are carbureted, very simple 3 speed transmission with no overdrive, so the engine is always turning much faster than newer cars (which is why another carb. V8 wont help MPG. it will still be revved up) which is why the new stuff has 6 and 7 speed transmissions. Best options to make current 360 get the best gas mileage is make sure the choke is working correctly and opens completely, keep up on the tune up stuff, make sure you have no vacuum leaks, and best fuel mileage tip is the keep creeping up the timing, basically what I do is set the timing 4 degrees above factory spec, take it for a 15-20 minute drive on the hwy, atleast 75mph, exit the ramp and then accelerate normally and listen for any spark knock. If none is audible, (listen very close) when accelerating after a hwy drive, I advance the timing another 2 degrees so now 6 degrees more advanced from factory, and repeat until I hear slight spark knock, then turn timing back (retard) 2 degrees and set it there. I have found that some I can only advance about 4 degrees above stock, and some I have turned up as much as 10 degrees above stock. This will also give you better tip in acceleration and quicker throttle response. They do make multiport fuel injection kits with intake manifold for these, but $1500 and up, and if your Jeep is already running in tip top shape, you will be lucky to see another 1-2 mpg. Very little spark knock is ok, but lots of spark knock can damage the engine. A GOOD EXPERIENCED OLDER mechanic knows this trick as they used to do this to every car back in the day (1950s-1980s). Now if you are willing to part with a big chunk of money, I have seen several different engine swaps, many of them being diesel, most common is the cummins 4bt motor and people claiming 18mpg hwy with those. To do that you also need a adapter to bolt the engine to the trans, with some internet searching, you can find companies that custom build adapters, you just tell them what motor your are trying to hook up to what trans, and they build it for you but expect to pay upward of $800 or more just for the adapter. Now the engine bay is large, it will fit just about anything you want. I have even seen a gm 6.5 turbo diesel in one before and that is a big, and extremely heavy engine, esp when you add all the accessories. My choice if is was to do a swap would basically be a complete GM ENGINE AND TRANSMISSION swap from a Pickup truck or SUV. I would do the engine and transmission so you can get the extra gears (overdrive). You can get any GM LS series V8 engine which include the 5.3L 5.7L (camaro corvette gto) or 6.0L from 2000 to present. I would choose that engine family because it is light weight, probably the most common engine ever made so you can buy anything for it, cheap, very reliable, fuel injected, good fuel mileage, small package size, decent power and very easy to find performance parts for, as the engine family has a huge aftermarket following due to the engine family being used in gm performance cars like corvette gto camaro. My dad actually installed one of these motors into a 1973 Truimph TR7 that he races, and that is one tiny car and it fits just fine. You use all the GM brackets, sensors, ignition, and fuel delivery system, and computer, aftermarket company even makes a special wiring harness for that motor all precut, all you do it plug everything in, and there is just 1 ground wire and 2 hot wires you hook up and your all done. I mean if your gonna do that, expect to pay several thousand bucks on the drivetrain, and then some ambitious elbow time, some custom fabrication at some point like hoses, and mounts. And my source to get all this, I would be a wrecked gm truck or suv. It would be cheaper to buy a wrecked car, than buy the engine and transmission, doesnt really make sense to be able to do that but I know this from experience. Ok, now that I have rambled on forever, I hope this gives you a few ideas or atleast something to think about and consider.