Small Block & Big Block Chevy Specific - Head gasket problem ( pics)

I have a 406 and water is leaking into cylinder 5, there is chunks missing between 1 and 3, and 5 and 7 I'm not sure what caused this, how do I keep it from doing it again? Any help would be greatly appreciated.
http://i886.photobucket.com/albums/ac61/jgh64/f24f966d.jpg

http://i886.photobucket.com/albums/ac61/jgh64/77f41e55.jpg
http://i886.photobucket.com/albums/ac61/jgh64/e5d559b6.jpg

Get you a straight edge and see if the block and head are true. It looks like something is not flat and decked like it needs to be.

Its sharing compression from the looks of that gasket and that is like puttting a blow torch in there on the metal between the cylinders. Its sure to not be flat now.

Could the motor be running lean causing detonation and taking out the weakest, thinnest part of the gasket? All 3 like that I don't think it started out as a deck that wasn't true but as stated above-certainly now it's not straight.

Well I took the head to the machine shop and had the surface it, I'll go pick it up tomorrow and see how much he shaved off, the block is zero decked

As mentioned you could have had preignition that killed it. I would probably pull the other head off and check it too. If its like that one that side the other is soon to follow.

if the block is still straight and the heads can be shaved some I would look into running a better gasket than that felpro replacement. Also what type of bolts are you using?