They are definitely both big heavy plants but mine usually don't get much bigger than 6 feet because they get taken down by blight in August.

Play it by ear. See how yours grow. You can adapt as necessary by staking, etc. Gardeners have good imaginations, and we usually come up with something. Some just let plants sprawl.

My Brandywine in my climate can get to 8 feet if not taken down by early blight.

The height of any indeterminate depends largely on your soil, temperature, growing season length, etc. It's hard to say exactly how tall they'll get.

I agree with JustGuy. i will say that with the right care you can probably get them to 10 feet.. it's not unheard of especially with the right fertilizers.