Help with finishing touches

*Heaving breathing*I have been on the most insane quest the last few weeks, I frikin hate genesis 9 but I love the material and some of the shapes. With that said I have come up with a pipeline to convert the genesis 9 to genesis 8.1 an was successful*tired*. I am just missing one piece of the puzzle, for the process to work I couldn't use the genesis 8.1 uv for the conversion process for the material, I had to use genesis 8 uv, there was visible seams with all sorts of problems, for some reason the genesis 8 uv works better. The problem I am having when I apply the converted material to the genesis 8.1 is the head, I do know about the process of using the "base female" instead of the "genesis 8.1 female" uv but the problem is this. I am exporting these models after converting to another program that is where the problem happens. The UV has to be the same, they all need to be genesis 8.1 uv. There was a guide a few years ago by IT roy on how to convert genesis 8 uv to genesis 8.1 but I cannot find it, also there are no guides on how to do this process anywhere. Only how to how do the torso to the head uv process. Does anyone know how to convert the material for the torso to the head while keeping the UV the "genesis 8.1"? Much appreciated.