Nothing to special here in Michigan with 1 exception. You can file a form 1 and when approved turn it into an SBR.
All the normal federal stuff applies and you can decide if you wish to file the Form1 as an individual or as a Trust. Normal NFA/SBR stuff.
The only thing to be aware of, if the SBR is less than 26" overall, the state of Michigan considers it a pistol, and Michigan has pistol registration. Of course you would have already registered the mp5 pistol when you moved into the state so that's a moot point, but it's important for people building SBR's from stripped receivers or chopping something like a PS90, once they are bult they are Federal SBR's. but state pistols and need registered if less than 26".