GM's HEI works great, but I've always been a fan of the stock look, so I prefer the Pertronix setup.

There's also an outfit that can convert a standard distributor to an HEI (known as the small body HEI).

The Pertronix setup is affordable, and eliminates points. It has 2 wires to hook up. It can be installed with the distributor in the car, but it's far easier if you pull the distributor. You'll need to make sure you don't have much up and down play in the distributor shaft, because the Ignitor magnetic ring needs a specific clearance between the ring and the module. It's always good to remove that play anyway with some distributor shims, whether you go to a Pertronix or not. The car will also start much easier (and faster) with the Pertronix. BTW, I use an MSD6AL box with a rev limiter.

As for carbs, there's always a lot of opinions on these, but if you have the patience, the Q-Jet is very hard to beat. And with gas prices as high as they are, it helps economy using the spreadbore verses a square bore design.