If you are not using a flat tappet cam, you don't need it. If you are, not not sure why anyone would a flat tappet on a rebuild, or you still have the stock cam, then ZDDP Plus with whatever oil you like. I used regular Castrol, half dino, half syn, and ZDDP at every oil change the last 10 or 15 years.....Broke crank due to other reasons, not oiling related, torn down motor and everything looked fine, even the dredded #3 exhaust lobe. I have been using Comp 980 springs also so the valve springs were not worn out.
Every engine now days and probably for the last 20 years has used roller cams, EPA has been mandating stricter and longer emissions warranties, I think its now 100k miles...its the heavy metals in the oils that was burning up the cats, so they have been eliminated in modern oils...heavy metals are required for flat tappet applications...so not just turbo Buick motors, but any engine you have or old car you have needs to have ZDDP added at every oil change to have the proper heavy metals needed for those lifters.