The lock will require re-keying but will be a very simple procedure. Here is the lock. I'll put up pictures of the re-keying a bit later.
The key blank is the R profile which is a match for a late bus (to 1979) engine hatch lock. Available off ebay.
The cylinder after removal from the barrel. I've removed one of the wafers and so one of the springs can be seen in the slot the wafer came out of. The other wafers can also be seen. It is these protruding wafers that prevent the cylinder from turning within the barrel and thus locking it.
Re-keying the lock will simply be a matter of switching the wafers around after the key has been cut. I'll cut the key to a random pattern then switch and remove some of the wafers as necessary so that none of them will be protruding when the key is inserted.
Above/below: the lock with the retaining screw removed. With it out it is now possible to remove the cylinder from the barrel.