Invented the wheel lately?
Just kidding, sometimes the obvious isn't obvious at all especially when you're going for a game strategy/victory condition you haven't tried before. So what you posted works perfectly in the context.
By the way, isn't it 75000 on Epic and 150000 on Marathon? Or am I remembering incorrectly. Lately I've played only on Normal speed, but I've had cultural victories on both Marathon and Epic. Very late cultural victories. Basically I didn't want to go space-racey and was bored with all the wars needed for domination, and my early wars haven't given me too many allies. Except once when I won a diplomatic victory a couple of turns before the cultural even though I haven't built the UN and haven't tried to influenced the AIs. They just liked me that much. Go figure.
Also congrats, manwiththehands, on your first cultural victory!