Well, if anyone's still listening, success! Had the 235 babbitt running today, three times, idling for about a minute each time (had to fill carb bowl each time). He shall live again after god knows how many years in suspended animation. Amazingly, looks like the carb is still working fine! And the skies were rent asunder and his name appeared before me: Lazarus. Thanks everyone - updates at the 53chevy link below.