You might want to think of putting in a little tour of the Septic barracks in Germany. Some of the fellas have absolutely marvellous jam-jars that they could possibly be persuaded to part with. Jam-jars, I might add, that have already had any conversions done to make them eligible for German road use.
No such thing as a classic american car.
If you insist on wasting your money on american rubbish, there are plenty of dealers down south in areas where septics are/were based who can save you the trouble of jerry paperwork.