they are SHORTER than the factory 68-69 piston CH is 1.920 , factory is 1.932 which puts it .003 in the hole on a blueprint deck .

I don't think it has a compression ratio listed but if it did it would be about 8.5 at .015 in the hole.

FYI in case you haven't been paying attention the factory OVERSTATED the compression ratio of the 68-70 , probably them all , at 10.0 compression , the only way to get that is to build to NHRA blueprint if using an open chamber head .