Hi guys I need some advice. I got a 1950 Chevy 3100. I'm getting ready to drop a 350 cu in with a th350 trans. Original gas tank is still in place and I think I'd like to keep it. Took sending unit out. Which was pretty rusted. Expected tank to be just as bad but it actually looked pretty good. Some light rust but mostly a black flakey coating. For lack of a better word it looked like flaking black paint and looked like clean metal under that. I've read so many different cleaning and dealing methods I thought I'd ask what was best. Vinager? Paint thinner? Sand or nuts and bolts rolling around inside? To seal or not too. Is it necessary to coat inside with a sealer or recommended? Local parts place has a red something or other. Should I keep with gravity red fuel style or plug it somehow and get a later model sending unit with the top gas line? Thanks guys.