Question about buying Carter BBD for my 318 (unless I should look at something else)

The 318 (on my '67 Monaco) might be in need of a better carb, the only one I've ever known is the Carter BBD. I see them for sale on ebay for relatively cheap, about a hundred bucks, they look nice and new.

So here's my questions. I see lots of Carter BBD's for sale but basically they boil down to 2 carbs. One type is exactly what I have, only one or twp ports, the accelerator pump linkage is visable. The other type has a raised box around the accelerator pump so you really can't see it, and a LOT of ports that I'd have to plug. I'm assuming the carb with a lot of ports is a more recent design? Does it perform better? (Performance, as in getting the air/fuel mixture right, especially when idling, MPG, etc).

My other question, should I ditch the BBD and look at something else? That is still 2 barrel. Something that might give better idle, and the best city/highway MPG possible? If there's nothing that stands out here, then I'm back to question 1 above.

Thanks for any input.