I see what you mean now. I think you'll be fine, if what you're worried about is enough meat to instal a horizontal CCI/Phantom-like stock class feed block/tube. Especially if you use the helicoils (and given what you're working with that I now see you definitely should). The rear section of the top of the body, where the rear half of the bolt is located, looks ridiculously thin, but this shouldn't be a problem or affect anything related to installing, drilling and tapping holes for your helicoils/stock class feed block/tube. You'll be fine. Good luck!