Whether your licensed manufacturer friend could put it together or not, he could not transfer it to you. All machinegun registration for individuals was frozen in 1986.
To turn an M3 receiver into a semi-auto, you first need to have the receiver, which means all the "hassle" of buying a machinegun. But no one who can buy a machinegun would want to convert it to semi-auto.
There have been a few semi-auto copies of the M3, but the ones I have seen were not especially good and the parts (or most of them) don't appear to be interchangeable.
Jim