I noticed in the script to start up OpenNTPD daemon, there are init script style commands to start, can these be replaced with systemd commands?
Of course they can. After all it's a Wiki. Just go ahead and make the changes you believe are required. If anyone disagrees with what you've done or wants to add or remove something they will make their own changes.
All men have stood for freedom...
For freedom is the man that will turn the world upside down.