If I recall, you are correct the turbine inlet and exhaust flanges use the same 8mm x 1.25mm studs, but I think there are only 3 studs on the turbo outlet. The rest of the holes are for bolts. Put studs there if you want idk.
You can also order studs from Mcmastercarr. Halfway down the page I write up how I specced out my new studs. Rated stainless steel > Frsport imo.
I used oval top nuts that lock when tightened. You'll be hella interested in those, and you won't need the washers then
. They aren't reusable though, so get a bag of them.
Thread:
Project PSU blue, running in the 90's! : 240sx General Discussion - Page 13
studs;
McMaster-Carr
nuts;
McMaster-Carr