With your model engine you may be in luck. The short block is made of cast Iron for your model--the heads of
course are Aluminum. If you can DIY this may be the way to go, remove the head--have it checked for warpage--have a complete valve job worked and then do the install--replace the Vanos seals while your at it also.
Now thats the way I would do it--if you purchase a used engine--may be better off--but who's to say--