Hi,
If you have correctly assembled and adjusted the shift shaft "barrel" nut, the only ratcheting you should hear is when you select forward or reverse from neutral. That would be the dog clutch engaging.
Question: Did you shift the transmission into reverse before disconnecting the upper and lower shift shafts from each other? The trans should be in reverse when disconnecting and reconnecting the shift shafts. The adjustment is also done in reverse. The only reason for this is that it fully exposes the barrel adjustment nut and the jam nut for easy access.
The adjustment is to thread the barrel nut onto the lower shift rod approximately 3/16 inch and then check for proper gear engagement forward and reverse.
You should never "dry shift" (shifting with the engine off) unless you rotate the prop shaft simultaneously. If you don't rotate the shaft the clutch dog ears can't properly engage and, if forced into gear with the dog ears not engaged, you could bend the shift linkage. It doesn't matter which way you rotate the shaft just so long as it's turning as you select a gear.
Also, many people don't realize that when shifting a dog clutch transmission the gears should be engaged quickly with a "crisp", fast movement of the shift lever from neutral to forward or reverse. The reason is this minimizes the clutch dogs from "bouncing" on one another.
If the gears are selected with a slow, lazy motion and much clutch chattering/ratcheting is being heard, the dog ears are bouncing off of one another and the clutch will quickly be worn out.
Welcome to the forum and
Good luck.