It has been done. Search for things like "modular 4.6" or "4.6 swap".
You can completely forget that 24 MPG, the Bronco has way more rolling and aerodynamic drag. Low teens is realistic. Don't kid youself into thinking you will get much more. under perfect conditions mid-teens. Although I don't thing 4.6DOHC and C4 will ever get into perfect condtions.
Also keep in mind that the power of those motors is up fairly high in the powerband. most people find driving a Bronco with a bunch of low end torque to be a lot more fun. But it is all about what you want and how you plan to use it. If your driving plans are for putting your foot down and keeping it would out, happy choice. IF you idle around and want controlled low end power, there are better options.
Then there is the other fun part. '07 has some fairly advanced electronics. Drive by wire throttle, etc. A friend who owns a dyno shop bought an '05 automatic just to play with. There were so many issues with hopping them up that if they got a little outside of there happy window they would shut down into limp mode. There will be a TON of work to get that engine to run correctly in a Bronco. It will want EVERY wire transplanted out of the mustang. While I have learned that this stuff is possible, it is not something that is recomended as a first swap. Do a few normal swaps, some basic early EFI swaps and lean the basics. An '07 swap will be a VERY advanced swap. You must understand the factory manuals and know what it wants to see. The days of faking a sensor with a resitor to make it run are almost gone. It expects to see the sensor change and if it doesn't, if it just sees a stuck signal, the computer will get pissy at you. Doing a swap of this caliber is one of those "if you have to ask if it can be done, you are not ready to do it".
Doing the modular motors has been done. But I wouldn't recomend it.
