318 to 390 hp?

I think if you have 360 heads you should lose the idea of 10.5:1. First, you don't need it, and second it may cause problems with a milder cam selection and pump gas. Go with a dished piston and bring it proud of the deck .005". Run any standard head gasket, and later if you want to upgrade to better heads any closed chamber head will be perfect. With a cam in the 230-235°@050 range you should expect around 400-430hp depending on the heads with some much bigger torque.