If you're going to go through the effort of opening up the carbs, it probably would be best to replace some rubber parts while you're in there on top of a good cleaning.
Close to 20 years of sitting probably means the rubber gaskets and float needles have gotten a little stiff. If it had gas in it when parked, ethanol or not, at least one of the pilot jets is probably clogged up, so I'm willing to bet you need to open them up to get it running right.
If you're on a budget you can take them apart and evaluate the condition of the rubber once you're in there, and not replace anything rubber that's still pliable and squishy. But I'd say it's unlikely any of the rubber is still in ideal condition.