Help with water pump

Hello, I am inthe process of replacing the water pump on my 78 spider, all hoses ,radiator, fan and nuts on the pump are removed ( exept the ones holding the tach drive). do these bolts need to come off? Because the one against the block is giving me a real hard time. what can I do to free up the pump from the motor? it does not want to free up.

thanks alot, Pat