you realize he has a 2000, right? the engine thing i was talking about is federal, not state...he cann do it, but if his insurance finds out, he'll have fun.
its not just engine/trans/rear- hell eed new springs, gauge cluster, ECU, all new wiring. plus the fact that the 5.0 was never OBDII which his car is will be a bitch and a half to adapt to. and god forbid he has to go outside his usual mechanic for work or anything, most wont touch it.
lets see...spend a shitton and pay for an assload of labor for a 5.0 swap, or just spend 3500 on a SC and get 300rwhp from the six which you can do yourself? seems simple to me. 4.6 swap will even only give him 220-230rwhp, unless he goes 4v.
If you want a 5.0, sell it and buy one.