This is about the only time that other guys will agree that 6 inches is too big
I'm assuming that you've already factored in a dropped base for the air filter (like the K&N filter in the photo above). Other than that, there's another 1/2" or so that could come off the manifold flange on the Ford version. Dropped engine mounts will lower the overall height some more.
I don't know the deck height of a Chev, but if you can't lower your engine in the chassis you may have trouble fitting the blower at all
Shame, because they are SO MUCH FUN to drive - and the sound of a B&M blower hammering away in the engine bay was worth the price of the blower in itself!!!