You will likely get more help if you have a mod move this thread to the dedicated theater design and construction sub-forum. As for a screen, you need to specify a budget and where your speakers will be placed (behind or around the screen). Screens can range as much as $50 (DIY) to $5000+. The X30 has tons of lens shift, so as long as you are close-ish to the top of the screen you'll have no issue getting the image to fit onto the whole screen.
If you want a high-gain screen, however, then your angle calculations become much more extensive and you'll need to look at the specs of the screen you choose.
A budget would help, though.