Update here: carb was definitely made out of pot metal, so there was some erosion throughout -- not enough to lose sleep over, however. Threw some baking soda on and it cleaned up real pretty-like. If any sleep was lost, it was entirely due to excitement: reassembled the carb and tacked it onto the manifold Saturday and got the General running for the first time in two weeks. Feeling pretty good for a shitty little pencil-pusher like myself. Thanks for the help guys.