It worked fine, but I was never really confident in the sturdiness of the setup. It seemed to hold in place very well, and I never had a problem with the mount shifting, but I always felt like I should check the sight-in every time I transported the gun. I ended up selling it to another member here on the fire.
Those screws are standard #6-32 threads. I have seen them in several lengths. I have one NIB and it has 1/4" allen head set screws. You can get them at any hardware store - usually.
The distance between the tips of the screws is about 1-1/8" The screws are about flush with the inside of the rear base. The distance will of course decrease as they are screwed in.
If that's not what you are looking for, send me a picture