At what point should I consider decking my 427 that I am in the proceess of rebuilding?

do it before boring/honing with deck plates. Most shops I've dealt with want a fresh surface to bolt their plates to anyway.

Tom

If you know what your stroke, rod lenth and compression height of your piston is they should be able to deck zero or leave some if needed and it should be done once the main line has been line honed and the shops that use a boring bar that sets on the deck can get a true 45 degree and a true 90 degrees to the crank center line.

What exactly are you asking?
When during the rebuilding process or if you should deck it at all?
I deck almost all blocks that I do & normally to a specific height depending on the parts going into the engine.
I do the boring & decking in the same machine so it is basically done at the same time & is done as Carl stated, in relation to the crank centerline.

Other than flatness, you deck to get the right piston to deck height for the parts you are using. My latest engine was decked once prevoisly so I got a pin height .020 down from normal and have my piston .010 in the hole.

Mike,

You answered the question as stated thanks.