2bbl conversion -- worth it?

Thanks for all the info. Ah, I hadn't realized that the 2bbl wasn't progressive... so what's the point of it, then? Better WOT performance, I guess. If it were progressive, I would expect better mileage than a 1bbl, because the primary could be set for economy, and the secondary for power. But if it's not, then I can see that it will just use more gas when you step on it (to look at it the simplest way possible).
OK, I also have a 2-to-4bbl converter plate. What if I used a Carter AFB? It has pretty small primaries -- I guess I'd want to compare them to the 2bbl. I am just bringing this up for discussion -- I am not really contemplating hotrodding this six, at least not until I sort out all the little niggling issues (why the wipers don't work, dash lights are so dim, etc.).