Many... of you have asked me about this lock. The original Beneteau lock is out of production, and IF you can get one of the people to scan the warehouse, it will cost in excess of $300.
As you will see in the top left picture, the Perko lock is considerably larger than the original. Notice the exposed screw holes.

To locate your replacement lock, take a piece of plywood approximately 6"x 6"x 1/2" and screw it to the door on the inside over the hole. Insert the lever into the overhead slot in the sliding hatch. (Just the lever, removed from the lock). Mark the center hole location onto the plywood. That is the center hole of the bottom of the lever.

Drill a small hole through that mark and you now have an external location for the center of your new lock. Using a hole-saw that is the correct size for your lock, insert the center drill bit into the 1/2" plywood from outside and drill until you touch the plywood. You should now be able to easily finish your installation.

Perko locks such as this, are available on ebay, West Marine, Defender, or almost any boat supply shop.