You got it right. Both of my ports are 4" internal diameter and each is 9.25" long. On the face of the baffle, I put a slight round-over on each of the ports by using a router with a round-over bit. If you decide not to do this then it will only effect the tuning by a couple hertz which is not a big deal in the grand scheme of things. When you build them you can try various port lengths and see what you like best (this is common practice for putting the final tweaks on a speaker).
For the link that you posted, I am not sure what tuning he was going for. It looks like he did a modified Pi4 build as well. For my build, I made the enclosure bigger and increased the length of the ports to lower the tuning (lower F3) to get more bass out of the 2226 driver.