Cylinder pressures have much more to do with needing head studs than boost. Running 20 psi boost but a lot of timing advance, at low RPM, etc will be really hard on parts.
My TT has a GTB2260 on a stock BEW long block running ~30 PSI and so far so good, though it does not see a lot of miles or continuous use. It also does not make much bottom end power which is easier on the hard parts as suggested above.
I think on PD's, you can just upgrade to 12.9 capscrews for a significant increase in clamping load (with the associated installation procedure) without a significant expense.
If you're not aiming for over 200 HP/300 ft-lbf, 12.9's are likely sufficient. If you're going for "big" power, then get the good stuff since there's so much time/$$ invested.