Example of what I have to work with-

[Chris in WNC]

Carb is Tillitson but not a Model A version.
They gave me the original Zenith-1 and said it was working when removed.

Fuel pump may not be needed- carb inlet fitting is about 8" lower than the outlet from the auxiliary gas tank.
They installed the tank backwards- the outlet is on the driver's side, making the fuel line about twice as long as it needs to be.

Seller told me the original tank did not leak, they just could not get gas to flow out of it reliably, hence the new tank and fuel pump.
Looking in the original tank I see no rust or varnish, just years of dust & dirt.
Will try flushing it out with acetone and see what happens.

It's an adventure.