Looks a lot like a Millette sight I have. I didn't know Mecgar made sights.
An Accro or Elliason rear sight from a Colt auto might work better. Mill a 'shoe' and silver-solder/dovetail it to the rear toggle.
S&W K & N frame revolver sights are nice and slim. Simple too - the sight is the spring. I've used those on 1911's.
