There is no way you will be able to fit an 11. The largest you will see is a 10.5 and that is with a 265 tire that will be stretched and will look a little too ricer for most, not to mention the hassle of offset and spacers.
That being said, I got a good deal on some wheels and I am currently trying to fit some 10.5 Cargraphic Racing wheels that were on a 996 on my 01 Boxster S. I took my car to Ruf and they tried but they couldn't make it work with the 285 tires that were on the wheel. We are going to try different tire size options today and see how they look and if we can fit them on the car.
If they don't fit then maybe someone on here will have an interest and want to buy them.
Getting larger wheels on a Porsche is a science. I would look for wheels in 9.5 just to take the guesswork out of it and no larger than 10 just to ensure proper fitment
Now if I could only just follow my own advice