Damien lives on one of the British Isle.......where he tells us that he can own a semi-only SA34 (MG34 that only fires one bullet with each pull of the trigger)........but his LAW will not allow him to own a full-automatic MG34...
Have you talked with Bob-Naess of Black-River-Militaria (?) He does a lot of work on these MG34s that are select-fire.....and there use to be one of our United-States that was full-auto allowed only (but not select fire) near him.
Also may want to ask Bob-Landies of Ohio Ordnance Works as he was doing a run of select-fire trigger-assemblies for the US M240 series..........possibly he has, or knows a way to modify an MG34 trigger-assembly to on be usable in semi-only (?).
If nothing else........try looking at (and thinking around the idea of welding off the area that the trigger-bar would move into for full-auto fire. This may allow you to use just the semi-only function (?)......just thoughts at this point.
US Army, RetiredBlanksguy2001@outlook.com
PS: Still looking for MGZ40, MGZ34, and parts/accessories for same.....