Oh, and dont use a tap for chasing the threads in the engine block. It's to sharp and will remove material leaving you with ill fitting bolts. Don't ask me how I know.
Instead use a thread chaser. It's designed for chasing threads without removing material. I picked up a set of them on Amazon. It is probably my most favorite tool set I have in my garage. I only wish I had invested in one years ago. Like before I took on my own engine build. At $60,which is kind of steep for a tool someone like myself who normally heads to HF for what I need, it has done its job many times over and still does. It's a craftsman brand set of male and female thread chasing dies/taps. It does NC,NF, and metric threads. In all the most common sizes ranging from 1/4"- 5/8" and even some 9/16" NC and NF. The metric is the same but metric. Lol. I'm sure there are other brands and configurations but it's worth getting the sizes that you will run across when/if you decide to take on the rebuild yourself. Just remember to always run them with some kind of lubricant.(threading/tapping/cutting oil, even a light engine oil. Not WD40, my opinion.) keep em clean. And they will serve their purpose for a long time.