Cleaning parts with any gasoline is asking to be on the news as part of a "freak accident". Your gas is now mostly varnish anyway. Drain it into a sealable container and take it to a hazardous waste facility for disposal. Be sure to clean the varnish off of the inside of your tank before putting fresh gas in it. If you don't you'll have bent pushrods at a minimum. The fresh gas will liquify some of the varnish which will then solidify on the intake valve stems when you shut the engine off. Many if not all will then be stuck shut so the next time you try to turn the engine over you'll bend pushrods.

Save a life, adopt a senior shelter pet.
The three main causes of blindness: Cataracts, Politics, Religion.
Name your dog Naked so you can walk Naked in the park.