Bryan:
Took a look at "King George V Class Battleships" by V.E. Tarrant, Cassell Imprint, Softcover edition 1999. A lot depends on when you intend to model the POW. As built, there was very little difference between the two ships with the exception that the KGV had an external degaussing cable on the hull and the POW did not. After the battle with the Bismarck, the two ships began to diverge a bit in terms of the light AA armament and this continued up through Dec 1941 when the POW was sunk including an ex-Army 40mm gun on the stern. The POW also had different camoflauge in Asian waters.
If your kit is of an early KGV, you should be OK, but if your kit is of a mid to late war KGV with augmented AA, radar, etc., you'll need to remove a lot of equipment to back date it to look like the POW. If the kit has the external degaussing cable on the hull, you'll need to decide if it's worth your time to remove it.
The POW seems to have had a very eventful, if short, career following the engagement with the Bismarck, ferrying the Prime Minister to his meeting with Pres. Roosevelt in Aug 1941, and providing cover for a relief convoy to Malta, before heading out to Singapore.
Good luck.