361 heads

I've made over 475hp on a pump gas 440 with a 230°@.050 hydraulic using ported "doorstop" 516s. They can be decent heads.
However - to the OP - there will be little to gain with going with a smaller chamber head on that 400. Spend the money on a decent cam, steel head gaskets(thin), headers, good exhaust, and/or ignition. It's much better spent.