instead of using weld to fill in the combustion chamber here are a couple of other options:

1) lightly machine out the affected area of the combustion chambers to make all six chambers very uniform, then have custom pistons made with an up set on the top deck of the piston that fills in the space required to get the squish desired. Another option here would be to find a piston with the correct diameter but has a compression height that normally would be too tall. Then mill stock from the top of the piston to get to the required compression height and remove a smaller amount of stock to get to the desired squish height and shape.

2) lightly machine out the affected arears of the combustion chambers to make all six chambers very uniform, then machine a set of inserts that would fit into the combustion chamber to take up the space required to get to the squish desired. The insert can be made so that significant edges of the insert go outside of the fire ring. There should be flush mounted set screws in the wings outside of the fire ring, but it is the insert wings being trapped between the block and head that actually hold the inserts in place. The fit of the insert to the combustion chamber needs to be tight, in the areas that cross the fire ring a 'snap fit' similar to the snap fit of a bearing bridge should be the goal. The area of the insert inside the combustion chamber can be left flush to the head deck or machined out to get to the desired squish area.

I am not saying I am planning of doing either of these, just some ideas on how a combustion with squish can be made without distorting the cylinder head by the pre and post heat required with welding.

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Doo Ron Ron and the Duke of Earl are friends of mine.....
https://www.youtube.com/watch?v=uX8Nj8ABEI8

I am always interested in learning new stuff. But I am wondering if all the work to get the squish is worth much at all on the track? Maybe it is? I know Mark's stuff run's like a rocket so I'm sure it helped some. Just wondering how much.

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2 Mopars come with Spark plug tubes. One is a world class, racing machine. The other is a 426 CI. boat anchor!

12.70 @ 104.6

Squish adds turbulence to the mix in the combustion chamber immediately before ignition, that turbulence will help to break up any remaining fuel droplets and mix them with oxygen for a more complete burn.
Squish also makes the area that the initial combustion takes place in less spread out, so the total combustion can happen faster and be more complete.

Imagine an 8 x 11 inch sheet of paper, and it is lite in the center, how long would it take for the fire to travel across the whole area and consume the fuel?
Now take that same 8 x 11 sheet of paper and crunch it up into a ball and light it in the center. To make this work one needs to imagine that the layers of paper in the crunched up ball all have the required oxygen with them for combustion. Can you see that the combustion is going to be quicker and more complete when the fuel source is in a compact zone even though the fuel area is the same.
This is an extreme case example, but it is how squish can work for you. Squish adds turbulence at the moment just prior to ignition and it makes a bigger hit possible at the moment of ignition.

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Doo Ron Ron and the Duke of Earl are friends of mine.....
https://www.youtube.com/watch?v=uX8Nj8ABEI8

One of the reasons (IMO) an early Hemi runs so smoothly is that it lacks squish.

I recognize the benefits of having 'squish' in an engine in terms of all-out power production. But I think, like most things, there is a price you pay for it. When you have a 4" bore and you 'explode' the fuel/air charge over on the left side, there's uneven loading across the top of the piston as it's being pushed down. The right side sees a deficit of 'push' as compared to the left until things have time to even out. I think this effect is worsened the higher the comp ratio is, too.

An early Hemi with 9.5 to 1 is a deathly smooth and mild running engine, assuming you haven't done all the usual hot rod tricks to it.

Yea but, the Gen 3 Hemi’s combustion chambers were modified to add squish, to get improve combustion and get a more complete fuel burn.
Then, I don’t know any Gen 1 or 2 Hemi owners that run that specific engine due to its ‘smoothness’.
Perhaps Ronnie Sox shifted so quick and Dick Landry was so deadly at the tree due to the smoothest of the Gen 2 426 Hemi. No doubt that Don Garlets started his Swap Rat dominance due to the smoothness of the 392 Hemi.

_________________
Doo Ron Ron and the Duke of Earl are friends of mine.....
https://www.youtube.com/watch?v=uX8Nj8ABEI8