I have a 46 model 216 and a 235 of the same year. I've never even seen the inside of a pre-1940 stovebolt, so anything I would say about the combustion chamber shape or volume would just be a wild guess.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!