Actually, the GM Training Center engineer I talked with about that conversion told me the only parts that will swap between the Toro-Flow and the gas engine are sheet metal items like the valve covers and the oil pan. None of the major parts are interchangeable, including the block.
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!