About the only major physical difference between a Ford and Chevy Holley carb is the auto trans kickdown. Yeah, other subtle differences, but what you may be 'experiencing' is attaching the throttle linkage to the wrong place (lug or hole) on the side of the carb. Have someone hold the throttle pedal all the way down(or use a brick), pull the air cleaner and look down the front barrels. If they aren't fully open, you have a linkage problem (the back two wont be open). Then, as with anything rebuilt, all is NOT always OK.