High HC on California smog test

I have a 1986 Honda Civic DX 4WD manual trans with a carburated 1500cc engine. It has 156,000 miles. The first smog test it failed HC at idle with 179 (120 is max allowed). It passed at 2500 rpm. So I changed the plugs, cap, rotor, air filter and the breather filter. I also pulled the egr valve cleaned off the carbon and vacuum tested it. It holds a vacuum. I checked and corrected the idle speed and timing. I took it in for a retest and the HC are down to 139 at idle, thus it still failed. After telling the tech the work I did he suggested a new catalytic converter. Is this my best bet, or should I try a new O2 sensor first?