3.5 into e30

my m8 is talking about putting a 5 series 3.5 engine in2 his e30 320 (1 of the late 1's) we should b able to get it in easy enough make up engine mounts if we have to,

i was just wondering about the wiring, does the whole loome need changed or is there ne way u can just plug the 3.5 brains in.

any help would b much appreciated,

thanks