I have managed to get Korganizer to display the contents of my Google calendar using the correct link from my Google calendar, but it was strictly a one-way relationship; I was unable to get modifications to Korganizer to modify my Google calendar. It wasn't a big deal with me, because I rely primarily on the calendar via my phone.
According to this link, a Google calendar resource now ships with KDE. I have not yet experimented with that, but I will.