I have been looking into this for a long time now. The 5.0 will be much cheaper but the 4.6 will be much easier. Also, if you go with the 5.0, you could reuse a lot of the same hardware from the v6, such as driveshaft, power steering pump plus lines, alternator, radiator, and even the transmission with some modification. The v6 T5 is actually rated stronger than the 5.0 T5. The things that make the 5.0 a much harder install is you need to swap fuel tank, pump and lines and also the k member. That alone has me leaning towards more to the 4.6. You can reuse all fuel lines for 4.6 but you will need a new power steering pump, ac compressor, alternator, HYDROBOOST, radiator fan and coolant reservoir, 4.6 transmission and driveshaft. k member is the same. New gauge clusters, ac lines, clutch and flywheel, ENTIRE EXHAUST (unless you already have true dual exhaust), computers, and wiring harnesses will be needed for both. Also, once you swap all of the parts, the v6 engine and transmission could be sold for $600~$1200 (depending how patient you are) I have once found a 1995 5.0 for $700 and all it had was a seized smog pump. If i were to swap it, i could have actually gained money in return! Your best bet definitely is to find an entire donor car. I have found a 2002 GT in perfect condition (even the body) except the motor had a knock for $1200. A block with decent mileage (no more than 120k) would cost around $400 so the price to swap a v8 into a v6 mustang really isnt that crazy. Now, if youve never done some serious work, then this may not be a good project for you. You will need a lot of tools and an engine lift for this. If you were to begin this project, you most likely would not have a car for up to a month if youve never done an engine swap. Oh! you will also need to add stiffer spring up front for the extra weight of the engine. and an 8.8 rear axle is highly recommended cause the 7.5 will go out very fast. Ask yourself, will you enjoy the feeling that you did this swap forever or do you simply want a v8 and dont want to go through the hassle of selling and buying a car?