New to the mopar world,Need help with 318 build..pleeasse..

The thing is i cant find any closed chambered,no 302's,and exactly how much is a lot of milling,will rocker shafts be affected,lifters,p-rods,springs?the heads i have are 596's,how much milling exactly with those,and where would my comp-ratio be at with stock pistons?also what do stock 318 pistons look like,any valve reliefs,castings etc..???i read somewhere they had four valve reliefs??am i wrong,or are those earlier 318's that have those,mines is dated 10-18-71