I have both of those ratchet adapters. I purchased mine used and I took them both apart to verify mechanical integrity and to replace the original dried up grease so they would function properly. They are regular right hand threaded, and I used the tips of right angle Knipex snap ring pliers to unscrew them. If you use snap ring pliers like I did, they do have to be the right angle type. Straight tipped snap ring plier jaws can't clear the female square drive end of the ratchet adapter and fit down into the ring pin holes at the same time. If I remember correctly, the ring just screws down and bottoms out against the top of the machined ratchet teeth.
There is no torque value that matters for that ring. Just snug it up tight enough so it won't come unscrewed on its' own when you use the ratchet adapter, that's all that's needed. The less torque you use, the easier it will be to get it apart again in the future, so don't overdo it.
The threads on that ring are quite large in diameter, so it doesn't take much corrosion in the thread channels to make the ring very hard to break loose and remove, so make sure you really need to get into the ratchet adapter before attempting it if the ring isn't unscrewing easily. You don't want to break the tips off of $25+ pliers just to fail at getting inside the ratchet adapter. If the insides are in good mechanical condition and the ring is quite stuck in place, you should be able to get it working smoothly again by letting motor oil seep into the seams overnight. That thin oil will loosen up any existing hardened grease and allow things to move freely again if that's the main issue you are having. If you are able to get the ring off, put a little anti-seize on the ring threads before re-assembly so you are less likely to have removal issues in the future.
If the ring is quite stuck, another alternative is to use a small pin punch that has a tip small enough to fit down into one of the pin holes, but instead of dropping the tip vertically down into one of the pin holes, set the pin punch tip partially in one of the pin holes at a 45 degree angle. Then tap the back of the punch with a mallet or hammer in the direction that will loosen the ring threads. That will give you a better chance of getting it broken loose if it's really stuck, because it will introduce an quick impact shock force to the threads which might be enough to overcome any corrosion. That procedure will deform one of the pin holes a bit in the process though, so only use that technique as a last resort if the ring is hard to remove and you really need to get inside the ratchet adapter.
I just did a quick test in my shop-
Knipex 4421J21 snap ring pliers fit my Snap-on F-67 perfectly.
Knipex 4421J31 snap ring pliers fit my Snap-on S67 perfectly.
