It'll be narrow, so you'll have to be careful with how you arrange your seating. If you want a second row, the riser will have to be fairly low... that means the screen will need to sit a bit higher than normal. There's a riser height calculator on the dedicated theater thread.
Due to the lower than normal ceilings, you'll also have to choose a projector that allows for a good deal of vertical lens shift adjustment. That would automatically rule out most DLP projectors, as they mostly have fixed image offsets for 8 foot or higher ceilings. And you'll want a flush mount ceiling bracket.
One thing to consider is a projector with a long throw lens, so you could mount it behind your seating so you don't have to duck.
Another point... since the room is 40' long, you'll want to strongly think about walling off your main theater section from the rest of the basement and keep it dedicated. Otherwise, you'll wish you had different speakers like Seaton, Triad, Procella, or other brands and multiple subwoofers designed for large home theater spaces.
The only other option would be to start looking at different houses with generous, open floor-plan walk-out basements (usually can accommodate 9 foot or higher ceilings) or at least those with below-grade basements with standard 8 foot ceilings (if you're lucky) that could easily handle a home theater environment.
It all depends on how "in to" home theaters and "man caves" you are. Personally, I'd keep looking.