everything leaks

Some of you may have read earlier that I have purchased a 1980 KZ 750 to match the 750 LTD that I purchased in 1980. After several improvements and a complete carburetor cleaning and new float bowl gaskets, (OEM, not generic ones that never fit properly.) I am now trying to get the bike started. When I put gas in the tank everything leaks. Gas leaks out of the tops of the float bowls. Gas leaks out of the nipple on the bottom of the float bowls. Gas leaks out of the bolts that hold the petcock on. I sanded the bottom of the tank where the petcock is held on, and the area of the petcock which attaches to the tank with a square block up to 600 sandpaper. I have never heard of gas leaking from there. There is nothing on the schematic that indicates there should be any kind of a gasket or sealer there.  All four of the floats were submerged in water for about two weeks. When released they all floated to the top.  I am curious that maybe the generic float valve does not reach the bottom of the brass valve that it fits into and that is why gas keeps pouring in. I have read in previous posts about float bowls warping, but I don't think that is the case here. I know there is a way to adjust the level of the gas in the bowl but I still think that maybe the float valve is not working properly. Maybe the clip is keeping it from bottoming to stop the gas flow. The generic rebuild kits for this model fits so many other models also. OEM float valves cost about $46.00 each. I would gladly buy them if I was for sure they would work. What to do here?

Thanks for the help.

Do you have the nylon washers that go under the mounting bolts for the petcock?  Number 17 in the diagram.

www.partzilla.com/catalog/kawasaki/motor...el-tank-80-kzy-50-e1

Missed that one, thanks