closed chamber vs open chamber

AJ/FormS said
I think that calculates out to about plus 6.5% power increase and plus 9% torque, with an additional 400 rpm at each point.
That looks to be worth about one cam-size, or a bit more?
Since we have been talking about chamber shape;What might the compression and squish differences have been?

This was a really low compression engine. With the 906 heads, the pistons -.160" deck height and .039" gasket thickness we had 7.5:1 compression and approximately .299" squish.

Using the 516 heads we bumped the compression clean to 7.85:1 and shrunk the squish way down to .199".