You have the bare and incomplete bones of the action, which appears to have been acid-cleaned and to have the start of a major weld repair.  To the good, factory-engraved Sharps actions (as yours appears to be) are truly rare.  To the bad, given the action's overall condition (especially of the engraving), its excessive incompleteness, and my experience as a restorationist, to bring this action back to being complete and functional would require a great lot of time, money, skill, and luck.

In short, what you've got is a "relic" and there's no dishonor in leaving it that way.

Bill Lawrence