The pics are a little fuzzy, have you tried to move the clips inward, away from the rivets? Something else to try is remove the float pins, slip the floats to one side and see if the lift past the clip one side at a time.
Look up the forum user billdramp on the forum here, he has several 350's i was just at the shop today and forgot to dig into one of the carbs laying around.
Good Luck