The plugs being wet indicate two different problems: overfueling or lack of ignition.
First of all, dry the plugs with compressed air or replace them. Get everything put back in ready-to-run condition.
Since you had problems with the fuel tank (I'm guessing rust) maybe a little piece of rust got into the needle and seat of the carburetor, which then floods your engine out. If you can, shut the gas off at the tank and try starting the engine. It will run for a little bit with what fuel is left in the float bowl. If it runs fine until the float bowl empties, look at the carburetor, particularly the needle and seat.
As far as intermittent ignition testing, hook a test light up to the (+) terminal on the coil and ground the other end of the light to the block. Try starting the engine. If the light flickers more than just slightly and goes out at the same time the engine dies, look at the circuit feeding the coil. If this checks out, hook a timing light to the high tension coil wire. If it doesn't flash every 1/3 turn of the engine, either the coil is bad or the points are not getting a signal to the coil.
I would be more suspect of the carburetor, especially since you had to replace the tank. It takes just a small piece of debris to hold the needle off the seat, and that WILL flood things out every time.
Let us know the results!!!
