[ACK]

Here's the little that I know. There's a lot of variations on the Rochester B, if the carb still has the triangular identification tag, that's your best place to start. If it's missing, I can tell you 2 things, the pump plunger is a different style on the earlier Rochester B (the earlier style uses leather, the later is plastic) and the jet for a 292 is around .072 vs. roughly .058 for a 250. There's not much else to distinguish them other than manual vs. auto choke.