The reason to pull the stock 8.4:1 pistons and replace with 9.5 dished was 1 Exhaust valve rotator failed and a valve kissed the piston at idle and we shut the engine off. Engine had not run in 5 years so we did a quick fire and in 5 minutes of idling to get to temperature it went THUNK and we killed it. Valve was wasted and the guide was bad too.
We bore gauged the block and found it well in spec. We then mic'ed each piston and the small diameter ones went into the A bore's and the fatter pistons went in to the E and DD bores.
So, again, someone school this stupid foke.