I have the same understanding as Ron, the factory relief was an effort to limit detonation by lowering compression in truck engines, not an effort to improve power. Note that this method of lowering compression preserves the quench between the piston and head and doesn't suffer from the misery that was the 1970s attempts at the same thing by using dished pistons.
Ford flathead V8 chamber design is an interesting subject, and most of the top racing engine builders will not share what their development looks like. Kudos to Bored&Stroked for doing that.
I stumbled on another flathead Ford racing chamber design earlier this year while wandering around the Model T regions of the world wide web. Apparently one of the Kloth combustion chambers from the race motor in the celebrated 1950 Mercury sedan got used as the design for a new Model T high compression head. Link to the web page here:
http://hcgarage.net/T-Head.htm
Picture of the combustion chamber, note the larger portion of the chamber is on the intake side:
