I just took another look at at the situation and made some measurements that might help. There is plenty of room for the rear element of most 210mm lenses. It can protrude up to 40mm from the back of the lens board. A lens with a front diameter of up to 64mm could pass through the tracks. The tracks themselves could be opened up to 70mm. Unfortunately, the front element of the lens, including any filter attached can only protrude up to 40mm from the front of the lens board for the case to close and latch. The case door could be "relieved" to allow a longer front element to pass through. Put your lens cap on from the outside and go your way, or fabricate a "nose cone" mounted to the door to cover it.