I am working on an 80 motor for someone.
I pulled down one motor and although it was marked KD it had been converted. It had 3 flat top 4.5" pistons marked C228C. Those are not in the parts book I have. He found a 4.5" flat top piston that they said was M&W but the marking doesn't say that directly. This piston is significantly heavier than the 228C pistons so much so I am working on balancing them.
It also had one flat top 4.25" piston marked C228F (gas piston). The head showed it had probably dropped a valve and I am guessing 228C pistons weren't available.
The other motor was a KD motor with 4.5" cupped pistons marked C228E.
The chamber size on the gas and KD heads is different. KD is supposed to be 4.5 compression ratio and gas 5.5. I don't have everything back yet but i have estimated the 4.5" bore (flat) with the gas head at 6.2. I think I estimated the gas head with KD piston at around 5.8 but I am a little fuzzy on that.
The Oliver markings are cast into the inner base of the pistons and could probably be viewed through the inspection covers. (You might have to clean some crude off.....)
RT (I think I caught all my typos.)