Im in the same boat with my 77 I recently bought..Now there are alot of places to look for a 2b intake manifold, but I would start with http://www.jwjeep.com/
for a used one, they are good people. Remember that you need to either match it with your exhaust manifold by year, (70s, or 80s) or get a matching set of intake and exhaust and do some minor exhaust work.
I had to go through this to deal with the howell, Im just not going to mess with the smog gear, I tracked down some of it, and still missing alot, not mentioning that it gets exspensive fast, all to run like crap with all that crud on it.
I decided that I wanted to upgrade anyway, so I got the howell, and a new HEI, and gonna get wrenching this weekend.
Ill let you know how it goes. Let me know if you have any parts you are looking for smog wise, I ended up with some parts that it doesnt look like Im gonna use.