[Oztrich Boy]

The Bismarck was actually largely based on a late World War I design, and had numerous design flaws, including very poor anti-aircraft armament, and a weak stern.

Designed for refighting the Battle of Jutland

[rmlew]

Are you certain you are not thinking of the SMS Fürst Bismarck, a never completed Mackensen class battlecruiser?
According to Jane's Battleships of the 20th Century, the Mackensen class battlecruiser and the Bismarck class fast battleship were quite different. They carried 350mm (13.8 inch) cannons, not the 15 inch ones of the 1940 ship. Also they had a displacement of 30,000 ton full load instead of the 50,000 tons of the later Bismarck.
You might as well be calling BB-56, USS Washington, an update of BB-47, the unfinished Colorado Class battleship in so far as they carried the same name and both had 16 inch guns.