gas tank repair

[rigger]

I have an oversize tank that is leaking right next to one of the brass inserts that holds on the petcock. The plastic is just thin in that spot and it is now a small hole.

I made a little aluminum plate that covers the area just fine. I just have not come across a gasket material or a sealant that will hold up to race gas.

Does anybody know of a sealant or gasket material that I can use? Or a method of repairing the plastic itself?

Thanks guys.