The H44 with 20' guns would no doubt be slow, unwieldy, and a very inviting target for planes. Massive guns would be more suited to a line of battle, which in WWII never happened. Ships were too mobile, aircraft powerful, the H44 would be almost completely useless.
The H39, however, was fairly well thought out. 16' guns were more practical, left more room for AA, and ship would undoubtedly be faster. But it would still be obsolete in the settings. Heres a list of battleships sunk in battle during WWII
Hood- By Bismarck
Bismarck- Torpedo bombers followed by Nelson
Prince of Wales- Air attack
Repulse- Same air attack
New Mexico, Arizona- Total loss by aircraft
Conte di Cavour, Littorio, Caio Duilio- Torpedo Bombers
Musashi, Yamato- Aircraft
Royal Oak- U-47
Fuso, Yamashiro- Failed Trafalgor-esque battle, sunk by numerous battleships
Graf Spee- Damaged by cruisers, then scuttled
Scharnhorst- Damage by cruisers, then Duke of York
Kongo- Submarine
Hiei- Damaged by aircraft, then scuttled
Haruna- Aircraft in harbour
Kirishima- Damaged by ship, then scuttled
Tirpitz- Aircraft
Ise- Aircraft
Hyuga- Aircraft, then run aground
Mutsu- Spontaneous naval combustion
You can see that the majority were sunk as a
direct result of air assault. Still not convinced? The ones that sank by battleships were at battles lacking air power completely.