Factory
Rebuilt
Carburetor

I'll make a pretty large wager you have an incorrect carb for the 235 engine. If it happens to be calibrated for a 216 instead of a 235, it will run very rich, and if the power valve happens to be stuck in the open position, you will use massive amounts of gasoline and have very low power. Do you still have the carb it was running before the head rework?
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!