It's my gun and the receiver is interchangeable with a cast Springfield. The gas system uses a different these pitch, but this could be swapped as well. Can take a USGI barrel and bolt.
I understand that, but you asked. The receiver was still made as an M1A receiver. The ATF and presumably MSP would likely consider it an M1A no matter what you did to it. If they contacted the manufacturer about the serial number, it is going to show as an M1A.
I prefer not to rely on a good lawyer facing a felony charge if there ever was a reason for MSP to investigate one of my guns.