Carb swap questions
I would also recommend finding a super six exhaust setup. Here's an extremely helpful link:
http://www.slantsix.org/articles/supersix/article.htm
Read up and research! Pull-it-yourself car yards might have the components, or if you are a machinist, fabricate your own linkage!
Is your car manual or automatic? If its automatic, you definitely need a kickdown linkage. The original carb with a super six was the BBD, very reliable in terms of design and function.
You'll notice a night and day difference with the 2bbl on the slant six. I for one would love to do the setup. The best advise is to take your time and do research. "Do it once, do it right." is the attitude I always take.
Best regards!