Hello
Just keep in mind it takes alot of machine work to convert an MG34 from full auto, open bolt to semi auto, closed bolt firing. Unless you are a talented machinist with access to the proper equipment, or have a friend who is, you are looking at contracting a considerable amount of expensive work. Not saying it can't be done, but it would be more economical just to buy a converted TNG MG 34. The bolt has to be extensively modified (there are kits available) along with the receiver and virtually the entire the trigger mechanism as well as the custom fabrication and fit of several critical, precise pieces. The MG 34 is a first class piece of craftmanship and the parts that are required to be modified have very, very precise tolerances..a 'close enough' conversion just won't work (a certain T2 comes to mind.....sorry, could not resist). And then there's the logistics of having it verified by the RCMP and the excitement associated with that once you are finished.
Here's a link to the US patent describing the process of what's required for converting a full auto MG34 to semi auto -
https://www.google.com/patents/US6634129
As for donating it to a museum for a tax credit - I am a former museum manager, so I have insight to that world. While we were not offered any machine guns at the museum I worked at during my time (though we had several in the collection), I was well aware of others that were. And I can tell you, man oh man, it was a nightmare of paperwork at the request of the CFO. In a specific example, right down to submitting a detailed plan, subject to approval, of how the firearm was going to be transported from the donor's location to the museum. Then there was a review of the museum's security, their security system, their collections management policy, their display policy, a review of staff who would be handling the firearm, terms and conditions on how it was to be displayed, ect. After it was done, the management of the museum reviewed the process internally and decided to never again accept a prohibited weapon into the collection. Long story short, there are a lot of aging collectors with historically important and expansive collections of prohibited firearms who will be finding themselves in the same boat as the OP of what to do with their collections who are assuming a museum will readily accept their collections once they are gone. Sadly, this is just not the case.
In regards to museums, the unfortunate truth is that A) the Legions are closing and are already actively donating their collections to museums that accept prohibs B) most museums that accept prohibs are getting filled up with donations from the Legions, so unless it's something spectacular, they will most likely have duplicates and not be interested OR the items do not meet their mandate and C) unless the museum specializes in militaria or firearms and has policies in place for procuring, securing and displaying prohibited weapons, they will most likely not accept them.
Someone earlier in the thread commented something to the effect that most people who have the certification to purchase an MG 34 already have one. I have found this to be true with prohibs. It is a buyers market for prohibited firearms right now as collectors of a certain age are starting to downsize or pass away and the market becomes flooded. For example, at a recent Saskatchewan gun show, I witnessed a transaction where spectacular numbers matching, vet bring back 1940 P08 Luger, in the holster with spare numbers matching magazine, traded hands for $300. And they buyer did it reluctantly as 'a favour', because he 'already had a few and you can only shoot one at a time'....Why did this gem sell for so little? Shrinking market of available purchasers. Now take that same P08 and (it hurts even to write this) weld it up, and suddenly it is available to everyone, licence or not. Now anyone who ever wanted one has access to it and you have a competitive market where the only cap is the buyer's wallet (or wife!). And there is a very strong market for dewat military firearms outside the firearm community, especially in the re-enactor community. Believe it or not, there is a market for dewat MG 34s among Star Wars fans who dress up at comic book conventions - in the original series, the storm troopers used modified MG34s as props! For the die hard fan, an original MG 34 modified to look like a blaster is a must. There are Star Wars fan forums similar to CGN where people have want ads looking for dewat MG34s!! I kid you not!
https://www.washingtonpost.com/news/checkpoint/wp/2015/10/20/the-real-world-small-arms-that-inspired-the-weapons-of-star-wars/
With the MG 34 in question, unless the OP can find a buyer with the required certification or a museum willing to accept it , the only options I sadly see are to salvage parts for re-sale, dewat it and sell it on the open market as a display item. Sad actually, the MG34 is a masterwork of precision craftsmanship and engineering, but it is what it is in this day and age.
Take care, all the best.
Brookwood