The 71 engine has been rebuilt, but never installed in a car. I've heard it run, and things seem good, oil press, etc. The rebuilder said it now has flat top pistons and a valve job and all the regular stuff. It has 99 heads. I was thinking of installing roller rockers to help out, but since I would have the valve covers off anyway, well You know, one thing leads to another. I wonder what, if anything I should do to the 6X heads to have aC.R around 9. to1.