small problem with the holley 350 on my slant 6

If the car has not been driven much, then before adjusting the valves, I would do the following to check for stuck valves, especialy where the pushrods were thrown: Slowly rotate the engine by hand and as each rocker comes back up from pushing it's valve down, make sure each valve comes back up to the top of it's travel. (You can use a straight edge across the valve retainers as a rough guage for this.) And, check the pushrods as pishta suggests for bending. If bent, or even not, then you could have sticking valves.

Is there ANY old gas left in the tank? The gum in old gas can do this. If you have any doubts on this, then you need to try to work the valves loose, and then clean up the oil system.