Here's a wild suggestion for you, how about 12mm head studs?
Before you say no, here's how I got there
7/16 = .4375" * 25.4 = 11.1125 mm
1/2 = .500" * 25.4 = 12.7 mm
and
12mm / 25.4 = .4724"
FWIW there is a dissertation on why studs are better on Pg 36 pf their catalog.
Their Catalog Here If you don't buy that how about just the beter quality metal that's usally in a "performance" fastener (better than grade 8 and better quality control).
I used to race liquid cooled VWs, we couldn't keep head gaskets in those without head studs either (early non cross flow cooling).
Just a suggestion so take it for what it's worth.
Hope it helps.
