I'm 6' and have an Impreza WRX wagon, which is a bit more cramped inside than the Foresters I've used while mine was in the shop. I don't have the seat all the way back, and my head isn't anywhere close to the roof, even when I adjust the seat height to the max (I usually have it set fairly low). I don't have a sunroof, which helps. But I just moved over 5 days from Massachusetts to Arizona in my car, and I was comfortable in the seat the whole time. Even felt ok during my last 36 hour push, when I avoided a hotel and slept in my car when needed.
The seat fabric in my '02 is different than that in the Forrester, but the shape and firmness feel very similar to me.
But the only way to know for sure if you will be comfortable is to go on an extended test drive with it. Maybe even do the negotiating with the dealer while sitting in the car.