My son has me really nervous now. The first thing he said after we hung the frame was "wow, that screen is really big. Do you think people sitting in the first row will block the projector?" I hope not. At this point, that would be a catastrophe. Hopefully I am not attempting the impossible with my low ceiling height and big screen size.
Wow you aren't kidding, you used almost all of the vertical space there! I'll cross my fingers for you as well. Your projector will likely have to drop really low from your ceiling. I initially thought I was going to use a very small down-pipe for my Chief mount, and ended up having to drop it twice to get the picture to fit. Since I used the zoom method for the two aspect ratios, I tried to fill the whole screen with zoom first, to get the width right, not realizing that when I zoomed out to get the 16:9 image, it would need to shift the lens down even more, and the 16:9 didn't fit. So I needed a longer down-rod. I think in the end it was 10". In the end, the projector was about 6' from the top of the riser, so if you didn't pay attention, you could hit your head. Even so, I had a good foot of space between my stage and the bottom of my screen, even more so. You may have to prepare yourself to drop your projector further than you anticipated. Then again, it also depends on your throw distance too, I didn't look at your thread to check if it was about the same as mine. I think Lowes/HD sell pre-threaded 1' downrods which are 1.5" NPT. Otherwise you will have to get them to custom-cut one for you if you can't find the right size. That also assumes you are using the kind of chief mount I purchased, yours might use a different setup.