Iron Clad-

With respect to power improvements, I highly recommend California Bill's Chevy Speed manual. It shows step by step the HP vs. RPM curves starting with a stock 216, evaluating each upgrade all the way to a drag racing setup- very cool.

http://www.amazon.com/California-Bills-Chevrolet-Buick-Manual/dp/1555611060

After reading this, going with two-single carbs is greatly preferred over one two-barrel carb, (much better volume/flow at the high end) and dual carbs with a mild cam is by far the biggest bang for the smallest buck. Dual exhaust does add some at the high end, but that's more for the cool exhaust note than for power.