You might wish to give this venture quite a bit of thought before you plunge into it.
Bolting on 2 or 3 carbs will look good, but unless some engine modifications are done, will not improve (and could make worse) engine performance.
Typical mods might include better exhaust, a different camshaft, ignition changes. More serious mods would include compression, and some lower end work.
Choosing carburetors to fit the particular tune of your engine will give much better results than simply throwing on some carbs.
Using two carbs means running simultaneously. This system gives excellent results, but is more difficult to initially tune (once tuned, should be bullet-proof).
Three carbs may be run simultaneously; or as a primary (center) and two secondary (ends). Easier to initially tune, but worse performance than 2 carbs unless you get serious with other engine mods.
Jon.
