Because of the smaller displacement, the 500 doesn't suck on the carbs a much as the 550 does. Jet needles are a different size/profile and the emulsion tubes have different holes sizes. 550s usually have #38 slow jets/ 500s have #40. If your 550 carbs are from an F model, the needles are yet another profile and the mains are #98. The 500 has 100 mains. There can also be differences in the idle screws, too depending on model. The difference will show not with whether it runs, but how well it runs at all throttle settings.
Of course, if your bike is not in stock configuration, some or all of the stock carb settings may not apply. But, unless you know how the changed components behave compared to stock, it is best to begin with stock settings, test, and change the appropriate aspect of the carb metering system and then focus on the next until the spark plug color is correct for all throttle settings.
An engine running too rich will foul the plugs. And engine running too lean can get preignition or even detonation, breaking bits of piston rods, etc.
You wouldn't be the first to assume that the carbs work the same on the inside because they look the same on the outside. If you just want the engine to make running sounds, slap the carbs on as is and pray.
best of luck!
