As DrAllis indicates- in general- basically yes, peripherally no. I would say if someone is willing and able, you could usually change over the parts you need off an original engine/application.
An example- we put a Cummins 8.3 out of a truck in my combine. Fuel system was different, so switching that was recommended. But the front housing that the injector pump hangs on was different! To change the front housing the camshaft had to be pulled. To pull the camshaft, the rocker arms had to be removed, and the cam followers held up. etc. etc.