'Splain this to me, Lucy.

Just to clarify- keep in mind that not all '72s were the low-compression motors. Early year '72 still had the 10.5 forged crank engines and phased into the 9.5 versions later in the production run. To confirm it is the late motor, check your balancer- it will have a cast-in relief with the words "for cast crank 340 use only" or similar statement.