I went with the 11 inch. It will require a different air cleaner than the factory manual setup. Here's a pic of my setup.
the guy above me has a factory air cleaner for the power brake setup and that is what I would recommend. They are unfortunately super rare and as far as I know you can't get an aftermarket one. I've never seen one for sale but if you were to find one it would likely be on the parts board here. That's where I got my factory ps bracket. They do make factory ps brackets but man they are ugly, and way overpriced! Back to the topic lol, yes an 11 inch booster w/bracket will fit, but not with an original air cleaner. Hard to say if it would fit with the air cleaner you have, it would be real close.