Mechanically I don't think it would be an issue. The "Yoke" and camera ball seem to be the same. The issue would be the sensors. I'm not sure if you could get away with changing only the sensors. You may have to change the roll and tilt motors also. You can't use the sensors of the CGo3 on the CG03+ gimbal board. The sensors have to be matched to each individual board, and cannot be swapped, even between identical cameras.
I am not sure the wire length is the same, but if anything I think the CG03 wires would be longer than the associated CGo3+ wires. The main thing is getting the wires plugged back in to the correct sockets. The boards are very different, so you have to know which wire goes to which socket on each gimbal board.
If it was mine, I would just use the CGo3 as is, rather than risk having two damaged cameras. If you have the tools and expertise, it maybe isn't such a bad idea to try it. I have never done this swap, but it at least looks feasible.