The honda ignition switches are common failures. It sounds very likely to be your problem.
Not the lock cylinder. The plastic switch. What happens is the plastic gets worn out from the metal spindle on the back of the lock cylinder to where it can no longer complete the turn to the spring loaded "crank" position.
The 1999 Vulcan 1500 has a carbureted engine and carburetors are often damaged by sitting with fuel in them. Since you said you "replaced the gasoline" that leads me to believe that you also left the gasoline in the fuel system during storage. That is almost certainly the problem here.
When Ethanol-containing gasoline is left it sit, it ...