Looking at the stock LT1 heads, I noticed a little approx 0.025 inch "shelf" in the area right beneath the spark plug. Looks like this may inhibit squish from that side of the combustion chamber. Or is there a possibility for improvement by somehow getting rid of the shelf?

1. So how much can stock LT1 heads be milled to essentially "zero deck" this part of the combustion chamber?

2. Or alternatively, has anyone built up this area via TIG weld, and then just had a very light milling of the heads to get them flat? This would also essentially "zero deck" that area of the heads.

It looks like if you did this, you might get a very slight increase in compression ratio, and a heck of a lot better squish area from that side of the combustion chamber.

All this would assume that you have zero decked the block so that you're set up to take advantage of the squish.