Pushrods

Per, do you mean to say that the adjustment screws are turned so that they are down towards the block as far as they can go? With the head milled, the likely problem with the screws should be that they are all the way up, not all the way down. All the way down says that the valves are too short, or the pushrods are too short, or the cam base circle has been underground a lot. What is your total lift at the valve?

Also, you have checked for coil bind but it does not sound like you have checked for clearance between the spring retainer and the valve guide.