My guess is that it may be a 3.8l but from the 996GT3 engine, just like the 3.8l was derived from the 3.6l of the 996C2.
I don't see how they can not have a dry sump on the GT3, the only advantage is that the 997S engine is cheaper but Porsche already charges more for the GT3 to compensate for the more expensive engine, but the disadvantages are much much greater; GT3 will no longer be able to use slicks, GT3Cup will no longer be derived from the street GT3 version since it will have a different engine, the similarity with a -20mm 997S with powerkit will be ridiculous, the GT3 fans and prospective owners will cringe at the idea, etc.

If you ask me, there is no way it will not be derived form the GT3 dry sump block...