If you are going to go through the knuckles and install disk brakes, suggest you also do the knuckle stud replacement.
http://earlycj5.com/xf_cj5/index.php?threads/148922/
The closed 30 is the same as the closed 27 shown here from the knuckle out. You'll also have the two-hole right knuckle, but functionally it's the same.
Also, IIRC you want the rubber knuckle seals instead of the felt ones? Looks like Crown sells both. OEM was felt. Don't put oil in the knuckles. A mix of oil and grease is often used ("knuckle pudding") or cornhead grease or other. Search on earlyCJ5 and you'll find hundreds of posts about this.