For the record my 67 FSM says 9.2:1, and my 1969 Motor's manual also says 9.2:1 for 1969 and older LA 318s. I have a 72 FSM somewhere, but can't locate it.
I believe the confusion here is the advertised compression vs "static" compression which involves measuring the compression height and cc volume of the combustion chamber but, I believe your advertised numbers are correct.