Carefully considering all the comments here, after operating P3B and P3C Update 2.5 airplanes for over 10 years (5,000+ hours), I think they are the 'ducks gutz', and I'm very disappointed Lockheed didn't go on with producing the P7.
I too operated P-3C for some years. In addition, I participated in the LRAACA program which was intended to replace the P-3. Douglas proposed a UHB powered MD-80 derivative, Boeing proposed a 737 derivative, and Lockheed proposed a P-3 derivative. After Lockheed won the contract, the Navy redesignated it P-7A. The P-7 had LOTS of problems, not the least of which was that Lockheed had based their proposal price on the estimate that the new airframe would be 80% or more common with the old one. As it turned out less than 2% was common, costs spiraled, schedules ballooned, and USN terminated the program for default.
Lockheed proposed a much more ambitious Orion 21 for the MMA RFP. But Boeing won that contest with a 737 derivative which became the P-8. Lockheed tried to market Orion 21 internationally and even offered bits and pieces of Orion 21 as P-3 upgrades, but got scant interest and no orders.