I've compared some high-res full front shots of the actual prop with my the cast I've got here and they match up almost dead on.
In some spots the lines on the cast are less sharp and less pronounced than on the screenused piece. In other spots it's is the other way round.
But then in other areas there are some things that seem to be present on the cast but NOT on the screenused piece.
The overall amount of texture is 99 % the same.
My conculsion:
It would be more difficult and time consuming to just only cast the details of the face and the body and leaving the rest of the surrounding are aside in order to just rebuilt it at the Illusive Concepts shop.
For the reason that LFL has NEVER allowed a licensed product to be a 100 % 1:1 copy, I think the guys back in the day made the following:
They've put some little amounts of clay on the original here and there in some areas where only the texture is in order to eliminate some characteristic features and in other areas to further pronunce them.
This way they can slightly alter the look in order to execute the politics of LFL not to bring a 100 % 1:1 prop to the fans.
Then they molded the whole thing . After molding they cleaned the original (removed the clay they added or whatever material they used) prop and voila, you have a slightly altered version which is now not 100 % the same as the orginal.
This would be the easiest way to do it. I think it wouldn't be suitable for the IC guys if they only molded the body without the textured surrounding area in order to resculpt that area in their shop.
Sounds a little weird but again, I'm german native speaker so plz. forgive my clumsy style of express myself.
Here is a quick comparison:
The red dots should mark a detail which is present on BOTH pieces. The green dots should illustrate spots which are more pronounced on the cast then on the screenused prop (and vice versa).