And you can definitely feel it seat in the pump drive. If you have any doubts, it's probably not fully seated. I'm always a bit surprised at how far in it tucks.
Then, just to be on the safe side, while you're lining up the bell housing alignment dowels, keep an eye on the converter to flex plate clearance. If they ever touch, you don't have it seated. Once fully against the block, you should have to pull the converter back out at least 1/8" or so to get it on the flex plate. Even if you KNOW it was seated when you started, you should keep an eye on that since it could potentially unseat while jostling the trans around to get it in place...