I have that Hendricks latch, heavily modified, on my Cozy IV. It is very pretty, flush from the outside, over-center on the inside, and works great. I purchased a right hand latch, flipped it upside down, and then machined entirely new internals for it so the over-center works properly. I even anodized it red, laser etched the LOCKED and OPEN arrow, so it looks very snazzy.
And I would never do it again. It is a pain in the ass to get it right. I think I made 3 or 4 of them before I was happy with it. If anyone wants the CAD file, I think I have it somewhere on my old laptop. If I were to do it again I would just do what Marc Zeitlin has on his plane, which is to say there is no external latch. The internal latch gets stopped by the key lock, and the rest of the internals are plans or very close to plans.