I got rid of three 200R4 transmissions, a couple of years back ... if I'm remembering correctly, all three had a multi-pattern bell that accepted BOP and Chev (all my transmissions came from 305 Chev powered G-body cars).
Sorry, my post isn't really helpful, just wanted to bring to your attention that there may not even be a Chev bell only 200R4 out there. If I'm correct, it'll make your search a little easier I guess.
-- Edited by pint and a pound on Thursday 2nd of April 2015 05:11:59 PM