Would it be hard to swap a big block chevy into a buick lesabre?

I have a 1985 buick lesabre and i was wondering if it would be hard to put a big block chevy into it. What would i have to do?|||why would you do something like that? spend your money somewhere else|||take it ta a deala and day can make it smalla like sharpen it down|||it'll take work..and alot of time, its very possible to do but you might have to lose some extra junk to make room and you might have to fabricate your own mounts to get it to sit right..and trust me when you get ready to put it in, bolt the transmission onto the engine first THEN put them both in...