I have replaced both heads on an air cooled vanagon without dropping the
engine (and on a '73).  I would do it this way again if I were confident
that I didn't need to do any work on the bottom end.  You can replace the
pistons and cylinders too while you are in there.

It will be worth the effort for you to be organized in the removal process
because due to the tight squeeze of some of the tin etc. you will need to
reinstall things in the opposite order of removal.

Although it won't be necessary you can free up the motor and use a jack to
raise and lower it a bit for extra clearance as you work.

Have Fun,

Jonathan Poole
'82 AC Westy