over heating problems

I have replaced the head gasket in our '97 pontiac trans port and did a tune up, when I start the engine it sounds like a loud ticking noise. Could it be the lifters need adjusting or change the oil again? Where should I start first looking? If I don't need to take it all apart again I'd rather not.

Yes: milky oil, also white foam on bottom end of oil cap , with overheating , all of this together does mean blown gasket....alas, 3.4 !!!