If you are doing the acetone treatment, I would suggest removing the gas cap to get it out of the way, and use one of those big test plugs they sell at the hardware store plumbing department. The kind with a wing nut on top, and a rubber seal that expands when the nut tightens. They seal tightly. After you drain the gas out, and you want to test if your plug is sealing, fill it with water, and turn it upside down, to check things out. Also, if you have some old petcocks, use those instead of the good ones, remove the filters, and in some cases, the sealer will dissolve, and let the stuff run out without plugging up the petcock. I've masked off paint jobs to prepare for the inadvertent bit of acetone that may get on your paint. If you do that, make sure it's secure, and you don't get anything under the masking. If you are going to paint it, no big deal, but I've removed several of these coatings with acetone, and have yet to ruin a paint job.