The project does not need anything for air superiority, the Morrow group is about reconstruction not making warlords.
They don't have a need for F-5s nor the ability to maintain F-5s, they like every other jet aircraft are maintenance pigs, not to mention parts and fuel are coming from where? they would become hanger queens within a month at most IF they even had fuel to begin with.
Light coin aircraft are what the Morrow group would have at most, I'm going with either Airtractors AT-802U
http://www.802u.com/
or Iomax's Archangel
https://www.iomax.net/archangel/
both raise absolutely no suspicion as they are made from agriculture aircraft, have very low maintenance requirements and flight endurance way beyond any helicopter or jet.
As for ww2 era aircraft made from modern materials I would go with Something similar that happened not too long ago.
There was a company called FlugWerk GmBH it was a company that had started building the FW-190 from modern materials, who recently sold off it's production capabilities to somebody else.
There is also Titan aircraft and it's T-51D
http://www.titanaircraft.com/t-51d.php
There is also the replica spitfires for those of you who prefer them:
http://www.campbellaeroclassics.com/...tybrochure.pdf
There are the people of War aircraft replicas international
http://www.waraircraftreplicas.com/
These aircraft are at 1/2 to 3/4 scale but people are buying and flying these things and it's not like you couldn't scale them up to full size.
There are even replica sopwith camels and the like along with F-86 replicas running around now.
So it is far from the realm of impossibility for the PBY, Goose or any of your favorite ww2 era aircraft to be rebuilt for MP (or anyone elses) use
Lighter than air aircraft have one weakness with helium and that is helium itself, unless you make it so that MP made a few of their fusion plants to create helium that gas is going to be as super finite as avgas would be for jets -assuming you even had any avgas.
You can't just keep avgas or any refined gas and call it good, it only keeps for a few years then is unuseable for it's intent and after 150 years there is not going to be ANY useable refined gas from before the war.
You will have to have MP design an alcohol or some easy to refine fuel to use in it's motor's if they aren't going to be fusion powered.