The best way to get the crank pulley bolt off is to use a breaker bar and socket and jam against the front chassis leg and flick the ignition key, however, I guess that it is a bit late for that now as you have disconnected the electrics.
So if it is really tight then you will have to lock the flywheel and the bolt should come loose using a good breaker bar and good socket.
Otherwise, attack from the front using a powerful impact gun and impact socket.