Quote Originally Posted by stovens
Paul I talked with Casey in Wa. today. He said they bored it over.040 and got 200lbs compression on each cylinder, so I think it should be o.k. on 91 octane pump gas. Let me know what you think. Steve.
It's not the cylinder pressure he was talking about. It's the squish. (distance from the crown of the piston to the underside of the head with the piston at TDC)

The way I understand it, blocks before 1972 were cast and machined with a block deck height of 10.300". '72 and later blocks were cast and machined with a 10.320" block deck height.

With Silvolite 1143 pistons, your "stack" calculates to 10.290". If the block is 10.300, that leaves a piston deck height of 0.010". Combine that with a (guesstimate) 0.041" head gasket and you get a squish of 0.051".

The same stack, if used in a 10.320" block, would yield a squish of 0.071" which would be too wide to make an effective squish in the motor and it may have a tendency to detonate.

I think that's what Paul was getting at.