I would remove the head bolts first.

I would also use the end of a breaker bar or a big ratchet and put that
into the exhaust or intake manifold. And then pry up ratchet get or
breaker bar. In addition, you could a putty knife and gently hammer it
between the head and cylinder block. You might even have to use a screw
driver.

If you turn it over using the starter the compression built
up in one cylinder might be enough to spring it loose.
Good luck.

You'll be wasting your time with a rubber mallet.  The first
thing I would try if the plugs are stil in is hit the
starter a couple of turns - with the ignition disabled, of
course.  A long pry bar stuck into an intake or exhaust port
will usually do it.  If it is really tough, a gasket scraper
driven in between the head and block.  Try to avoid a
screwdriver. That usually mangles the head or block.  If you
want to hit it with something, use a block of hardwood and
at least a 4 lb hammer - no point in just pissing it off.

Lugnut

Thanks to all who replied.  I was able to remove the head with a rubber
mallet.  There was just a lot of gasket seal holding the head to the block.