The blocks are interchangeable, BUT... The 24V used striaght-thread sensors with an o-ring seal. Hence the term "STORM" block which you may have heard. It stands for Striaght Thread O-Ring Machined. The 12V uses all NPT threaded sensors. And to answer the next question, no, the sensors are not interchangeable.
Don't bother with trying to repair a 53 block. Even with the lock & stictch it can still crack, just not in the same location as the repair. Get a good block, and don't worry about it!