Set the timing mark of the harmonic dampner on TDC by rotating slowly using the bolt head inside harmonic balancer (27 mm ?). Always rotate in normal direction of engine firing (look at direction of cooling fan blades). See if marks of cam spacer and mark on cam tower line up. If not, how much off are they? This will help to determine possibility of damaged valves. Before doing this, you may want to remove spark plugs to make it easier and also get a look at the valves inside possibly.