Shotgun Boogie Gun Works adjustable trigger kit for competition rifles, model Uberti ’73

Includes trigger, trigger spring, washer for the trigger spring, screws, pin and safety bar spring.

While this kit is easily installed, it is not drop-in, it requires fitting by a competent Gunsmith.
And most important: The position of the trigger IS NOT ADJUSTABLE!

See also the article in Cowboy Chronicle January 2015 from Larsen E. Pettifogger. Pages 36-45: