1970 Duster 225 to 340 engine swap

Hi I'm new to the site so I don't really know how this all works. So here goes... I have a 1970 Duster with a basic 225 and I'm about to buy the EXACT same car but with the 340. Will everything swap out as easy as pie (engine, trans. suspension, exhaust, k-member)? Or am I gonna need to do some modifying? I just want to have everything I need before I try to accomplish this so I can do it all in one weekend. Thanks.