The Lefever was mfg. in 1935.
If it is a double, remove barrel and you will see it along with serial #.
Requires professional appraisal.
Turn of the century.
The best that I can do is say that the Lefever Nitro special was made from 1921-1948.
Blue Book of Gun Values
To get a parts breakdown you would need to take the shotgun into a gun store. The store will be able to provide an estimate, or order new parts.
Lefever made several models through three different versions of the company. Not enough information.
The shotguns were manufactured by Ithaca from 1921 through 1947. Yours was manufactured in 1928.