Putting a red dot on the 99 is dirt simple, a piece of Picatinny from Amazon for under $20 mount it in the existing screw holes -clamp the red dot on...done in 20 min.
The (4, I would use either a Lyman or Marbles tang but you may have to D&T a hole in newer models of 94, they weren't drilled at factory. I have mounted & used many with only using the one hole (usually the tang stock bolt) to secure the sight, the curve of the sight base & stock wrist keeps them meshed & secure with only one screrw under normal usage.