My 440 block has been decked. I am not exactly sure how much, but I did have to use the "shorter" timing chain setup. The 906 heads may or may not have been milled over the 44 years. The stock aluminum sixpack intake will not drop down far enough to get all the bolts started, even without the bathtub gasket. Obviously, the intake needs to be milled. My question: is there an easy way to determine how much should be milled, and is there any validity to a post that I once read that these early Edelbrock six pack intakes were actually milled at the wrong angle from the factory. BTW the intake is 1970.

First off decking the block does not affect the timing chain needed , that happens after the block is linebored .

You should be able to figure out how much the deck has been cut by using math and knowing where your pistons are in relation to the deck height.

One thing that people usually don't take into account is that decking the block surface is the same as cutting the head surface , the cut that needs to be made on the intake side of the head has to be done also when the block is cut, the valley end rails also need to be cut the same amount as the head intake surface to get the valley tray to fit properly.

as far as your 1970 intake being cut wrong and that's why it's not fitting , highly unlikely.