ummm, guys it is not that hard, there are a few companies that make the adaptor for the T5 to bolt up to a 2.0-2.3 DOHC focus motor. There are a ton of advntages, lots of bolt ons, better gas mileage, and lots of horsepower for the weight, plus you are keeping the car a 4 cylinder, if you want a 5.0 go buy one, I never understood the people that will spend weeks and weeks and thousands of dollars to convert a 2.3 to a v8 when you can buy v8's cheap. You can buy 2.0 and 2.3 motors for under $500 and their are tons of them stuck in all manner of Ford, Mazada, and Mercury's.
"Ford's silver top and black top Zetec engines have been fitted to classic RWD Fiesta's, Quantums, Mk1 and Mk2 Escorts, Anglia's, Orions, Cortina's, even Lotus Europa's, Westfields, and all manner of kit cars.
Ford (being the sensible people that they are) decided to stick to the same bellhousing pattern that they have stuck to since the 1960s. So for a rear wheel drive (RWD) application, you can use the Type-9 five speed box from the Sierra, plus an RS2000 bellhousing. One simply bolts to the other. Note: The Type 9 has a 1" 23-spline input shaft and the 2000E four speed box has a 7/8" 20-spline input shaft. The MT-75 (Granada) or T5 (Sierra Cosworth) gearboxs also fit on the Zetec.
Zetec crankshafts are already machined to accept a RWD spigot bearing, which again simplifies things somewhat."
Plus you can use modified Range 2.3 motor mounts to install the motor in a Mustang without a lot of fabrication.
http://www.emeng.gentlyhosting.co.uk/MT75_Gearbox/EngGear.htm