Just thought I would throw in my thoughts on this topic.
Having had many chevy 6's, Gen II and Gen III, I have tried many ideas to get the most out of them. Some with success some with not so good results.
On the subject of milling the head; Gen II, if you are going to mill the head, angle milling can be of some benefit if you are willing to move the head to the port side of the block. Bolt holes must be enlarged and spot faced back paralell to the deck.
Also make sure you have not covered any water passages. Moving the head in this manor will put more of the chamber over the cylinder and allow more room for a larger dome on the piston.
This has proved to be a benefit in drag and round track racing.
Gen III can also benefit from this practice as it unshrouds the intake valves by moving the intake valve closer to the center line of the cylinder to eliminate the chamber overhange on the deck.
Little changes can have good results.
