318 head gaskets and water jacket holes

Scratch that again. I just stuck a pocket mirror near the backside of the head and the freeze plug is clear missing! No wonder water is pouring out of there.. damn.

Ok, while I'm at it do any of you guys know what is the "thinner" head gasket I can use on the heads? I had these #302 heads milled down .30 but when I put the heads on the car I used whatever head gaskets Advanced had available. Since I'm tearing the heads off again I'd like to really maximize the .30 with thinner head gaskets. Also wondering if while I'm at it should I have my machine shop go down another .20? Not sure if it'd be worth it but figured I'd ask. Thanks again!