[Lynn Eades]

Hi Darrin, I can give you dimensions for a standard British or Canadian (top)box.
The center catch (as you would know) is a little different (from the LP2 catch) because the pad lock hole is at the lower end rather than the centre of the catch. The end catches are the same as a Brit. or Can. one. The riveted hinge section is wider(with rounded ends) than the LP2 weld on type.
The internal lay out looks to be specific to the LP1, as is the wire cutter mount.
Your lower box will be the same depth / length, but your great photo has just revealed to me that they were side opening.
Let me know if you need anything from me.