No. Well maybe it's the easiest, but for the love of God, don't sand blast the inside, or any surface you plan on welding to.
It's a pain in the arse, but use a wire wheel, paint stripper, sandpaper, spoons, forks, anything but sandblasting to remove the paint.
When you sandblast it, it drives the impurities and blasting media deep into the metal, and then it won't weld worth a chit. You can still weld to it, but be prepared to do some serious grinding...