I'm not sure exactly why you would, but if you want the simple answer, not really.
Biggest thing is the motherboards are completely different shapes. The GBA board is larger, meaning it would require cutting to get to fit in the SP. Unless you're really good at working with circuitry and jumpering clipped MB traces, resizing the board will turn it into junk. This doesn't even take into account the different placement of the controls that will need to be readjusted; or even available space inside the case.