The D8OE chambers are 69 cc. I´ve got the block rebored at 4.030" and the piston (Speed Pro L2488 F30) are over deck height at 0.003".
With Fel Pro 1011, the quench height is 0,035". Then, compression rate 9:1

The original 1968 heads had 63 cc, rated 9:1 compression, with stoch deck height and stock dished pistons.