I hope you brought your A game and a big bank.
Just because it fits in a truck does not mean it will fit in a Mustang.
Read this first.
4.6 to 5.4 Swap
new engine,1.7 rocker arms,Pipes exhaust, shorty cats , shorty headers,under drive and overdrive pulleys,4.2 upper plenum, throttle body spacer, cold air intake, stage one clutch, shorty shifter, and tune. 8.8 in storage