I was too sleepy to do the math myself, I figured that some coffee guzzling, math whiz on FABO would "jump in". If you do a little research I'm sure you'll find the same chart that I saw, it shows that 67/68/69 factory engines all have the same compression....9.2:1. Maybe the difference was so slight the factory didn't care??? I know that the factory head CCs varied quite a bit.