reading the slant six plugs color

If you have the early slant head with that removable cup that the spark plug goes in, make sure to torque it to spec. Also what kind of camshaft do you have? And have you recurved the distributor, I believe your running on (dieseling) is due to too much curb idle and not enough initial timing. Being able to give it More initial timing will allow you to lower your curb idle. This is an issue that happened when you up the compression and don’t recurve your distributor. I would order the fbo limiter plate and set it at 18 degrees and take out the have spring and replace it with a mr. Gasket light spring, that should put you in the ball park.