Need new gas tank + whole system. Advice?

Meanwhile I removed the gas tank. Was quite an easy job.
Only had to cut one of the J bolt because at some point I couldn't lose the screw nut anymore.

Well, what to say. It looks like sh** from the inside.
I think the tank was swapped once, it is not the original. Also the sender unit I think.

Looks like the aftermarket tank and sender unit were not the best quality.
The sender unit rusted up in the down position.

Don't even know what this black stuff is inside.

Here are some pics.