A turretless Hipper could be fast but dangerously fragile

Could replacing both rear turrets with machinery and fuel push a Hipper-class cruiser beyond 36 knots and increase range?

Yes, perhaps to an extreme speed near 45 knots, but the remaining four 8-inch guns would leave the ship too weak to survive interception or air attack.

The machinery and fuel volume could create a very fast surface raider, but speed would not make it immune to aircraft or a determined destroyer attack. Once slowed or intercepted, the reduced battery would leave a large and valuable cruiser unable to defend itself against opponents it could previously fight.