273 Commando Piston Dome Volume

we can walk you through the .500" downfill method if need be- oh I see a link but have not looked at it
closed chamber heads?
agree on polishing those piston heads
original piston would not have been coated in 65- what you got there?
you might want to od hone those pistons or even give them a light knurl on the thrust side, run a bottle brush or brake hone through the pin bores- anything to hold some oil- lightly