91 gmc Jimmy 427 big block
 

Okay I'm new to this site and haven't worked on much in my life but I own a 91 gmc Jimmy s15 4x4 it currently has a 350 in it that's getting weak and I found a 427 big block that's very clean fresh rebuild how hard is it going to be to make this swap possible also has 6 inch suspension life and 3 inch body lift

Thank in advance
Dale mccullen