doesn't seem that complex to me, if the BBC head comes with a valve and spring setup for .600" lift they need to tilt the rocker stud to fit a 1.65" rocker correctly, I can't visualize what problem that change would generate, they all need specific length pushrods and stud girdles anyway, actually moving the stud say .050" might cause some interference issue somewhere but changing the angle seems doable to me
I didn't even consider the head manufacture changing the rocker stud angle. Like SteelComp said, they need to converge with the valve angles. I thought the question by Roadknee was more along the lines of changing the location of the rocker studs rather than changing the angle of them.
But do you really think that any head manufacture is going to use either a different angle or a different rocker stud location for every single customer and for every possible combination of rocker arm and lift range used? You used an example of .600" lift, but who's to say what's average, or even what lift the majority of customers are using in light of the multitude of camshaft choices there are out there? I mean assuming a .600" lift at the valve for most customers, (which is relatively very mild by today's standards in BBC builds even for pump gas street cars) would be like assuming that most guys who are willing to spend $3K on cylinder heads for their street/strip pump gas cars, aren't also willing to reach for some big power and bigger lift from a roller cam to take full advantage of that $3K that they just dropped on the new heads.
The point being, (again) that there isn't any specific standard when it comes tocam lift anymore. It isn't like back in the day when most guys just went to the parts department at their local Chevy dealer, and ordered either an L-88 camshaft, or a ZL-1 camshaft, because there wasn't a whole lot else to choose from in the way of ultimate street performance.