Just for info and not sure if it helps at all but when I had my GC8 with a front mounted GTX35R I simply had a 1mm restrictor on top of the turbo and a drain from turbo to sump. Nothing fancy just a -10AN (may even have been -8AN). I just let gravity do it's thing and the setup worked extremely well.

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605whp
Quarter Mile in 10.9 seconds @ 135mph /217kph
0-100 kph 3.2 seconds