So you know the "choke on" position will make it run. What you need to do next is to reach under the carbs and make sure the nozzles are popping back up when you take the choke off. Running the car with the chokes on, or they fail to release, for awhile can crap up the plugs. Have someone pull the choke on and off while reaching underneath the carbs to make sure the nozzles are returning. If they appear sticky which is typical of varnished up gas then douche out the nozzle tube with carb cleaner to hopefully free things up. All the can be done by removing the air cleaner. Other than that just running some fresh gas thru it after you get it running some, may help too...... No need to fart with float levels at this point. I seriously doubt anything has happened to change float levels just "sitting there"..... Let us know how you make out......