P38 engine help

Hi all I have a 4.0se p38 and the engine has totally gave up dropped liner warped heads and block so req new engine the thing I want to ask is will a 4.6 fit in without modification as I have been offerd a low mileage one they are both 1998 gems engines any feed back much appreciated also is there much performance difference in the 4.0 and 4.6

gear boxes are diffrent but do fit. 4.6 one is stronger. and you could use you loom, ecu ect. But im not 100%.