The US Navy recently replaced the P-3 Orion with the P-8 Poseidon.
While not the “Max” version, the P-8 is the 737 platform......which fly over my house every day. 😏
The P-8 is based on the 737-800 NG, which is shorter than the 737-900 NG and 737-9 MAX. It shouldn’t have those door plugs (which are there in case airlines want to max out on seating and convert the door plugs to working emergency exit doors) Also, the P-8 doesn’t have the bigger CFM LEAP engines like the MAX’s (so it shouldn’t have MCAS) The 737 NG’s are very safe planes. I think you should be okay.
The base aircraft for the P-8 is based on an early 1990s design, so the design itself is probably sound. Manufacturing is, of course and open question with anything Boeing is building these days.
If the Navy was going to abandon the Lockheed Electra, I always thought that Lockheed should have offered something based on the C-130 as an alternative.