5.2 magnum options

ok, I put a 5.2 magnum in my 66 valiant. it has a 904 w/a small stall 22-2400.
I have a miss that wont go away. swapped carbs, and the entire ignition system with zero change. it was rebuilt before I got it ( about 8,000 miles ago ). I have a feeling this is why it was pulled. im thinking it has a sticky valve or two.
do I just upgrade to the EQ heads? will porting help the stock lower end?
any suggestions for a cam? it currently has a larger than stock comp computer cam ( not verified )
I am running a 600 holley on a air gap knock off intake and have a set of shorty headers to install when it goes back in.
really just looking for a cruiser with some grunt that we can enjoy. car barely was used last year because of the miss.