If you are going to the (major) trouble of opening up enough to look at these components, you should simply replace them while you are in there. If you have then gone to the trouble of replacing guides and tensioner, why would you even think of putting the old chain back in? It's a big job. You should also think about things like the oil pump while you are in there too. Can't hurt to replace everything that's accessible while the front of the motor's off. My lack of specific knowledge of that motor may have just shown. I'm not really sure if the oil pump is there or not as it is on some others.