A couple of things worth mentioning. A very experienced machinist and engine rebuilder I learned under once told me that he never uses impact tools to tear-down an engine. His reason was that he wanted to feel the parts and fasteners coming off, they give clues as to why it failed. (If in fact it did). My reason is that I want to know if fasteners were over-tightened or finger-loose. If the engine has never been apart since the factory, it's less crucial but on this one, I really had to know.
I do not have access to a torque-monitoring wrench/device, (they cost 10s of thousands of dollars), I rely on my hands to check previous torque when removing nuts and bolts. Proper tightening torque on fasteners is important on all types of machinery but on air-cooled engines, it's absolutely critical. Air-cooled boxer engines are like furbies or chia pets, they are almost living things. They expand and contract quite a bit as they get heated and cooled. I haven't read the torque specs for this 356 engine yet but the head nut torque on a VW engine is something like 36 lbs. A little more than finger-tight. When the engine gets hot, they get a lot tighter.
It was hard to tell whether the head stud fasteners were over-tightened on this one because the previous "rebuilder" used some type of thread-locker/glue on all of the threads that really stuck them. I will reserve judgement until I get the skinny from the real experts but my experience is with assembling 911 engines and you definitely do not use glue on any threads, with a couple of notable exceptions. Not on head stud nuts, thats for sure. Half of the studs came out with the nut when turned, not the end of the world but not right either. If anything, thread-locker is used on the other end of stud, ie. in the case end.
Thread-locker glue:
A stud that unscrewed:
