The best we can give you is this:
Your concerns are kind of understandable, but the Matterhorn's clearances are nowhere near as low you're imagining them to be. (Off-hand, I would bet that both Space Mountain and Incredicoaster have lower clearances.)
Watch this and you'll see what I mean. This camera is (ridiculously) above someone's head - and it's still not close to getting clipped by anything. (I'm dying to know what they mounted it on.)
There's no way you're as tall as this camera is:
The main concern of tall riders is the comfort of the seat - they usually suggest that tall people get into a front seat.
If you're still nervous - the best you can do is just go to the ride, tell the ride operators your concerns, and see what they say. I'm 99% sure they'll sit you in the seat, see if you're comfortable, and tell you that you'll be fine.
But we're not going to be able to give you a definitive answer. As best as we know, you shouldn't have any issues.