I am copying a build a while back from hot rod magazine. Not going to reinvent the wheel here.
KB 167 pistons hypereutectic
Pre gapped Moly rings mogul’s
Magnum heads later models
MP single plane intake manifold
Comp cam 280H magnum camshaft
.480-inch lift
.040 bore oversize
1973 piston rods from 318 engines
273 crankshaft
Holley four barrel 750
TTI headers
Manual transmission
If you google “400hp 318 build”. You will find these exact same specs that I am using for my build.