They are both way too large, you need a 150 CFM carb for that car.
You can buy one here in order to keep the car stock:
Make sure you tell them is it for a 170.
If you want to "build" it a little, I would suggest you move up to the 200 for the 7 mains. Put a 250 head on it (better flow) and go to Clifford for some "go fast" parts/header:
If you're really serious, after you put in the 200, import a head from Australia that does not have the built in intake manifold and pick a free flowing intake that suits your needs.
You can't put in a 250 I6, it's too tall.
Moving to a V8 presents a whole lot more changes, I wouldn't recommend it.