Trying to figure out what brand this frame actually is
With a lot of patience (i.e., if your time has no value to you) you can try to match partial parts of the serial code (you probably find it under the bottom bracket) with serial codes on the site bike-index.org. This way you may (I stress, you may) have a clue about the original manufacture/assembler of the bicycle you are interested in.
My suggestion is to let it go, it may look like a S-Works, it may have parts that looks like a S-Works, but there is no guarantee that it is even properly assembled. In my opinion, it is likely to be a zombie-bicycle that will let you stranded in the middle of an intersection and consequently being maimed by a truck.
Good luck!