getting lower cylinder head off kz400b engine

been stripping the top end of this engine as part of a kz400b rebuild.

have got to this point:

ie. the upper head is off and I now need to lift the lower section off so I can take a look at the state of the pistons.
The workshop manual mentions using a screwdriver into small cut at the bottom of the head to wedge it away from the crank case. I tried this a little but no luck and I don't want to chip the casings. Any other suggestions? Thought about heating it up a bit with a hairdryer? Maybe blow air on the outside and maybe a bit directed inside as well to try to warm up the sealing compound that was used? It looks as if there isn't a gasket on the lower section but I could be wrong.
Anyway it's gone pretty smooth so far but this step has got me worried - any suggestions very welcome.

Gentle, I repeat Gentle taps with a rubber mallet did the trick on my 900. Wouldn't recommend hitting any of the "deeper" cooling fins for fear of breaking them.

cheers
Tom