However, if you mean swapping to the old 5.0 pushrod motor, the first thing you have to consider is whether your state allows you to legally swap a 1996 engine into a car that requires OBDII. Technically, it's illegal in all 50 states; however, if you don't have to pass vehicle inspections or emissions, who would know. The swap itself is physically possible & Muscle Mustangs (or another mag) did one years ago with a 95 Cobra R motor, but I wouldn't even attempt it unless you had a complete donor car to start with.
rancorkeeper has asked the right question. Which 5.0? Bringing up legalities is important. In Michigan there were about 10 prosecutions in total for this for years but in the last couple of years it's been over 200 a year and it's expensive. Arizona has been even worse.
If you're talking about a Coyote crate motor it's a fairly straight forward swap. Use the Ford control Pack to run the engine and get a Haltech Interceptor Module for this swap so you can use your current electronics for everything but the engine. For a pulled motor it gets more complicated and more information is needed to help.