Sending Unit Gas Leak

I have a CMC, a 1973 VW gas tank was used. I was told it had to be installed backwards. My problem is, the sending unit is too low and leaks gas if I fill the tank to the top. Is there a good fix to this problem? Can anyone recommend a good gas sealant?
Paul McGuffin, Green Valley, Arizona

I thought I solved this problem by using a gas proof sealant and a cork/rubber gasket, however increased tank pressure on hot days forced the gas out anyway. Soooo, I shit-canned the pressure resistant check valve at the breather hose on the filler neck. Then I installed about 10' of fuel line (looped to form a trap just higher than the filler cap). I ran the hose down the front fender well and along the frame rail to terminates in front of my right rear tire.
Wa La>>>> No more leak or gas fumes for me!

You got 2 possibilies. JB wield or the Eastwood tank sealing kit with the white sealant . It works pretty good. The JB wield will be harder to remove if you need to change units in the future.

The Loop vent idea is also a good upgrade. Ernies right

What do most people use for a gas tank in CMC? I guess you could custom build one, with a seding unit at the very top; just like the real Speedsters had.
Paul

Do what Ernie did. After several failed attempts with the same issue, the looped breather line (no check valve) worked best.