Carb size/ brand

Been a while since I've looked into carb selection. But carbs were picked by intended application. A 4500 might be meant for an IR manifold. Or two on a tunnel ram with a manual trans. My 1150 was intended for use as a single carb,modified class,auto trans. Variables could be,2 or 3 circuits, accelerator pump timing, style of booster, throttle linkage. 1 to 1, soft,progressive. Power valves and so on. The closer you fit the app the less mods needed.