Base gasket leaking on fresh rebuild

I just bought a 719 stoker kit for my 660 and got it all together and it was leaking oil out the base gasket so i tore it apart and tried again with new gaskets and i used copper coat sealant on it this time hoping that would do it and now its leaking again. I got the right length bolts in the right holes im pretty sure. But i just dont get it ive never had this issue with anything. am i missing something? Is there some big trick to these motors?

Base gasket leaking on fresh rebuild

I just bought a 719 stoker kit for my 660 and got it all together and it was leaking oil out the base gasket so i tore it apart and tried again with new gaskets and i used copper coat sealant on it this time hoping that would do it and now its leaking again. I got the right length bolts in the right holes im pretty sure. But i just dont get it ive never had this issue with anything. am i missing something? Is there some big trick to these motors?