Elitebook G series motherboard compatibility

Here is a curveball. Has anyone swapped out an old motherboard for a newer motherboard in the same series laptop? This is my extra backup laptop that I want to keep available. It’s an Elitebook 850 G1 and I’m only trying to hop one generation from an 850 G1 to 850 G2 motherboard. I cannot see any difference in dimensions or technology that would make a G2 motherboard incompatible except for possibly one thing: the G2 seems to have 3 USB ports, whereas the G1 (the older model) has 4 USB ports. Every other port and slot for power, SD card, the display ports, Ethernet are in the same location. Has anyone moved to a different motherboard but of the same general family, series, manufacturer? Thanks!