Trick flow rocker shaft studs

Very wise to use studs with alum heads. A few reasons. Most important is alum is a soft metal & by using studs, you can utilise all of the thread depth in the head for maximum strength.
If you need to add/subtract shims, you are not disturbing threads that might lead to stripped threads. I used s/s studs on a 440 with TF heads. Bought a length of s/s & cut the studs to the reqd length.