I have my 52 3600 cranking and running on first start now..... finally. Only problem is now Im noticing things. I have a valve knock coming from cylinder 3 it sounds like. Also around the spark plug a small puff of smoke will come now and again. I was told when the motor warms up a lot of the knocks go away. is this true? Also it sounds like I have a major exhaust leak at the manifold. All these combined, does this sound like I have a serious problem or is this expected with a truck that sat in a field for thirty years?

I know this is probably a dumb question but I am trying to get the truck running ok to leave for the wedding and I would rather not ruin the truck in the process but dont have time for a rebuild of the motor either.