That ratio was for the Speed Pro pistons not the one's from Egge Industries. What is the commando engine? This one doesn't have an adjustable valve train.
The 4bbl version of the 273 was known as a Commando (Plymouth) or Charger (Dodge). It had domed pistons, 10.5:1 compression, and a cam with .415/.425 lift and 248 duration. I'm surprised you don't know about this engine if you are building a 273 -- it would come up all the time when choosing parts.
AFAIK all 273s had mechanical lifters and adjustable valve train...?