AS I follow the listings on G/B for "MG34 parts", there are a couple of folks in So CA that typically advertise. One in particular has a ROOMFULL of MG34s on Lafette-34s. He just sold a latch, inexpensively.
I would get to know him by purchasing some random part...then breach the question.
The clamp is a mechanical answer to a simple math problem. Being lousy at math, I would solve it with cardboard cut-outs and tracings of the end of a shroud...and a thumbtack.
I did notice that the "latch" is similar to the clamp-on panzershroud accessories. The clamps are available from AAS Sniper98.
If you get them made, let me know. Good luck....Phil