KB976 was being prepared for use as a water bomber in Canada with some stripping out being done in preperation, then the plans changed and it was sold and flown to the Strathallan collection in Scotland.
Its now with Kermit Weeks in Florida, in bits awaiting restoration.
As for a Lanc on floats, the biggest around would have been some from a Dakota as desctibed here.
(The Edo Corporation, of College Point, N.Y. designed, and built twin, 1-ton floats, (the largest floats ever built). Each float was 42 feet long, five feet, eight inches wide, and displaced 29,000 pounds of water. The cellular construction of each float had 14 separate water-tight compartments. Each float also had a 325 gallon fuel tank. The floats had fully retractable, hydraulic wheels, and could land on water, snow or land. The float rudders were connected to the air rudder).
They potentially could have been modified to fit the Lancaster Undercarriage attachment points but a fully laden DC3 only weighs about the same as a empty Lancaster, therefore the floats would have been impossibly small.
Seems unlikely unless someone knows differently.

Richard