He's talking about adapting a Powerglide from a 1956 BelAir to a 250. He did not mention whether the PG came from a 6 cylinder or a V8. If it's from a 6, it would have had the adapter ring for a 235. If it happened to be from a 265 V8- - -AND- - - -the adapter ring was included, he's good to go. Either way, it's a whiz-poor choice of transmissions when so many better options are available.
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!