This is all I can find in the Municiple code:
Sec. 20-203. Possession of machine guns.
(a) It shall be unlawful for any person to possess any machine gun.
(b) It shall be an affirmative defense under this section that the accused is a member of one or more of the following classes:
(1) Authorized law enforcement officers in the performance of their official duties;
(2) The armed forces of the United States, including ROTC units and the National Guard in the performance of their duties;
(3) Any person or persons or corporation licensed by the federal government as a dealer in machine guns under the provisions of the National Firearms Act; or
(4) Any person lawfully purchasing and possessing a machine gun under applicable federal law.
(Code 1980, ? 20-203; Ord. No. 33757, ? 8, 12-19-95)
It looks to me like there should be no problem just so the purchaser gets the proper Federal permit. But that could be the problem, you don't need the Fed license to purchase the parts, but Omaha considers the parts to be a machine gun.