gas started dripping out of the left side carbs
Grit in the float seat/needle valve, most-likely. Contaminated gas. Drain the float bowls, analyze the crap that appears, check the gas tank, and you probably have a rusty tank, which will need cleaning and the easiest way to do that thoroughly is to remove it. Don't forget a new gas filter. The T-fitting gas line, which splits gas to each pair of carbs, is a good one to have on hand, as they age, any manipulation will break them. Have one on-hand before you start work on the fuel system.
Using a long ratchet extension to tap on the side of the offending carburetor's float bowl may allow passage of the grit from the float valve seat/needle valve. Think of it as the bike's 'kidney stone.' However, it inevitably will happen again, as the tank continues to shed rust material into the fuel delivery system.
A static display shouldn't have gas in it, so that may not be an issue if it's never gonna run. However, an empty gas tank will rust over time. You should fill it with something to keep it from rusting, maybe ATF, and attach a tag bolted onto the bike the ATF is in there, and needs to be drained, and rinsed, before adding gasoline. It cannot hurt to place a sticker onto the faux gas tank warning of the ATF, and one on the speedometer too. Redundancy!