If you are in the US, you have to be a Class 2 manufacturer to do so. You cannot just get a form 4 and "temperory" C-2 license to build a MG.
Or, you can do so and the BATF will give you a nice, private cage to live in for the next 10-15 years for free
Even after all the paper work, you still do not own that MG. Any MG made after May 1986 can never be indivdually own. Those C-3 dealers have two choices whenever they decide to quit the busniess: destory it or transfer it to other current C-3 dealer.
Call or go to BATF website for up-to-date info.