[Dick Shift]

FYI: In 30+ years of repairing Porsche's I have never seen a broken STEEL head stud. Even very rusty one's. $10 bucks say's your broken stud is Dilivar.
In my opinion you can safely drive [easy] with one or few studs that aren't side by side if need-be, while saving money for repairs. Bottom line if you heir an exhaust leak sounding noise when accelerating especially up hill, the leak has progressed to the point that cly. head damage will now be a factor.
I also don't feel it necessary to replace all the head studs. If money is a issue just replace the Dilivar, non magnetic, head studs. I use regular [cheapest] STEEL head studs. Good used STEAL head studs when available to save money still get my life time "NO BRAKE" warranty. Yes, life time!

Once the alt belt is tight but not too tight. It is important to have enough shims between the outer pulley and the retaining nut washer to keep the nut from bottoming out on the fan before applying force on the outer pulley half. Generally 3-4 washers should between the outer pulley half and retaining washer.