You may have said earlier but i cant remember if you did, i guess the question will be how hard are you going to run it? (boost and compression wise)
I dont have that much turbo experience yet, but the motor i built for my buddy Jim, we only used stock 8mm but havent pushed it pass 18lbs either. normally runs 15 now a days with a pinch over 7:1 cr and mild cam (in essence no overlap and low lift) and small ports that this 15 lbs that we do see has to make it through. (reading from the Tee section of the intake.) I guess its all reletive.
When I built my turbo engine, I started with a new brazilian case & it came with 10mm case savers alreadys installed. This would not have been my first choice as the 8mm allows better stretch. Back in 96, I got chromoly studs that where 10mm at the threads & tapered to 8mm in the middle from CB Performance. I Don't know if they still offer it, you can check. I struggled with what torque spec to use, the 10mm factory VW spec or the 8mm factory VW spec? I shot the gap & went with half way in between. I don't know if this was the right answer, but it must be OK as I've been running the engine since then OK. Hope this helps.