Sorry to be pedantic,but they're head bolts,not studs,unless an early model with 3/8" threads.
The "best practice" when building any engine,is as follows.
Run a standard tap down the holes to check they are clean.
Screw the bolts down just snug,without and washers,brackets etc.
Use the washers etc as "feeler gauges" under the heads.they should not slip in by some margine,if they do,or even come close,you won't get the clamping force on the bolts when tightened,the torque could be from bottoming,not clamping.
90 FT/LB may be ok on 12mm quality bolts,for the standard 7/16" bolts the figure is 60-65 FT/LB.
Early models with 3/8" studs 40-45 ft/lb.
Head bolts will age with heat cycles and stretch,but if replacing,I will always look for plain headed NOS ones.
Just my opinion,but the plain head screw cut ones give more thread engagement,than the CP drop forged or cold headed ones.