You're right Omaha not Wichita. I pulled the following off the CAF website:
http://www.cafb29b24.org/fifi.shtml
Fifi's official serial number in No. 44-62070. Some of the interesting dates in her earlier life are as follows:
July 31, 1945 ~ Delivered to USAAF, Salinas, Kansas.
August, 1945 ~ To 247th base unit, Smoky Hill Field, Kansas.
September, 1945 ~ To 232nd base unit, Dalhart Field, Texas.
October, 1945 ~ to 242nd base unit, (Continental Air Forces - changed in May, 1946 to Strategic Air Command), Grand Island Field, Nebraska.
April, 1946 ~ Modified to TB-29A, used for operational training.
November, 1947 ~ Status changed to "excess" at Grand Island and transferred to 414th base unit (Air Material Command), Pyote AFB, Texas. Assignment was "SA" administrative aircraft (probably some Colonel's private plane).
January, 1948 ~ Status changed to "SS" - storage (noncocooned) - polite for "left in desert."
October, 1951 ~ To contract maintenance and modification. Returned to B-29A configuration in April, 1952.
September, 1952 ~ Assigned to 310th Bombardment Wing (SAC), Smoky Hill AFB, Kansas.
April, 1953 ~ To Sacramento Air Material Area for depot maintenance.
May, 1953 ~ Returned to 310th Bombardment Wing (SAC), Smoky Hill AFB, Kansas.
August, 1953 ~ Assigned to 3510th Flying Training Wing (Air Training Command), Randolph AFB, Texas.
November, 1953 ~ Modified to TB-29A (trainer).
October, 1956 ~ Transferred to U.S. Navy (believed flown from Randolph, Texas to China Lake Naval Weapons Center, Muroc Dry Lake, California at this time.
1971 ~ U.S. Navy to Confederate Air Force and flown to Harlingen, Texas.
There is no mention of conversion to an a-bomb carrier. I doubt they would have had to move bomb racks from one plane to another while getting Fifi ready to fly, but anything is possible. It's probably just one of those stories that gets started.
James