Why replace the Q-Jet? It was engineered to work with the 350, and anything else will just be "different" not necessarily better. The aftermarket carb will be approximately right, IF, and it's a big if, you manage to get one that's close to the right CFM rating, and it's somewhere in the ballpark, jet-wise. If it's not, you'll need a flow bench, and a lot of years of experience to make it work. Most people buy WAAAAAY too big a carburetor, and end up with flat spots, backfires, and a lot of other nasty stuff to deal with. Then they make things worse with a single-plane intake designed to make top-end horsepower only. It's much better to stick with what was designed to work right in the first place.
Jerry
