I have been experiencing over boosting ever since I got the car back together. I installed a manual boost controller (MBC) in parallel with the n75 and the boost would still creep up, so I suspected a torn wastegate line.
I hooked up a air nozzle with about ~10psi and could hear a loud hissing from the lower passenger side. When I crawled under the car I saw that the wastegate line on the actuator had torn clean in half.
Removing the old line was not as difficult as I feared. I was able to reach my hand up from the front of the motor, underneath the exhaust maniflold and above the motor mount and slip the hose off the actuator. and installing the repaired line.
I cut the metal line just past the bend and slipped on a new vacuum line. I should have used actual wastegate hosing with some shielding but it was late and was leaving for a trip the next morning.
Installing the repaired line was much more difficult than the removal. The wastegate actuator nozzle was just far enough out of the reach of my hand that I could not get my hand to push the hosing on. It took about 20 minutes to finally get the hose on and then a worm clamp over it to secure it.
My hand looked like I had pulled it from a garbage disposal.