You may find that the Nova EXT from Premier mounts is what you need. You can remove the central column to keep the PJ close to the ceiling. It operates with a bayonet so you can easily remove the projector.
Hi, thanks for the replies. Sorry i should have mentiond the projector model. It is an Acer P1165 DLP projector. Here is an image with the mounting holes dimensions and where they lay on the bottom of the projector.
Very impressed with it, neat design, solid and fully adjustable. Also, you can simply rotate the lock and remove the projector and cover the remaining mount + wires with the white dome cover when not in use.